I probably mentioned this a while ago, but I have been changing the way I use Basecamp to make our custom routings on Basecamp. We like to choose the exact route to take so no GPS "freelancing" to roads we don't want to be on so it is certainly more difficult than just putting in destinations and taking what you get for routes.
There are a couple of weaknesses in Basecamp and the Garmin and other GPS units that have to be addressed if you want full custom routing without surprises.
First off is the whole idea of what a "destination" is. Garmin also uses waypoint. To most GPS units it is an absolute point that you have to go to and not miss it by even a tiny bit. This means that if there is a few hundred feet of road construction or a map error where you destination is placed to set a custom route, the GPS will never stop telling you to turn around and go that point. Garmin addresses this by allowing you to change "destinations" to "shaping points" (used to be called waypoints). Shaping points take you to the location, but if you miss it by any amount and then go back onto the route the GPS picks up the route right there and ignores the "shaping point" so no incessant harping from the GPS to go back to the point. It isn't perfect as sometimes it takes the GPS a while to realize you probably don't care you missed the point and it tries to lead you there by a weird path, but mostly it will get you to the route again pretty well. I don't think any other GPS units use shaping points and destinations unless they have just started doing it.
The second issue with Basecamp and even other map programs like Google maps is the drag and drop of the route often gets weird on you with crazy zigzaging back on forth. Basecamp is probably the worst at drag and drop, though. When drag and drop it creates a destination at each drop point and then recalculates the route to go to it, but it often then takes you right back to the routing you didn't want to be on requiring more drag and drops.
The changes I did in how I do routes gets rid of both of these issues nearly completely.
First off, I now don't put any destinations in the middle of a route unless we really want to stop there for some reason and don't want to miss it. I do put a destination about 100 feet from our driveway so we go through it right away, as that keeps the GPS from freelancing to final destination, which is does sometimes without the first destination but lots of shaping points. Then I put in a final destination. The route can contain dozens of shaping points.
I don't have Basecamp make a route for the near home destination to the final one at this point.
I have a pretty good idea how Garmin will choose to route so I just add destinations along the route we want to take to force the route to go that way. It does not have to perfect at this point. I choose the destinations in order along the route and add letters to the name Basecamp calls them as I go. First is A and the alphabetically after that in order. By doing this Bascamp puts them in alphabetical order in left side panel for that trip so they are also in the order we will be going though them on the route. The reason that this is so nice is that when you tell Basecamp to make a route through destinations you highlight it takes them in order that you select them or if you bulk select with select the first and then shift/select the last destinations it takes them in order that they are on the list. Right click on the selected area of destinations and click "create route using selected waypoints". The route is make with all the destinations in order and if you right click/open the route the details will show the points in the same alphabetical order on the routing. This is important because you may need to add some points to tweak the route or change it later on for some reason.
I look at the route and see if it is just what we want and if it isn't I just add destinations between the existing ones. If the new point is between D and E it would have DA added to the point name and it will show up on the panel list in the right place. To put it in the route just drag the point to over over the route in the left side panel and drop it on the route in the same left panel and it will be added to the route. Unfortunately, it doesn't put it in the right place on the route and always just puts it at the end. Open the route and highlight the point you just added that will be the last point on the details and then use the up arrow on the right side of the details to move it up to the right place. The letters tell you exactly where to put it. Hit the recalculate button and the route is remade.
Repeat adding as needed to get what you want for a route. Then open the route details and change all the points between the first and last destination to shaping points by right clicking them and selecting change to shaping point.
Next is a screenshot of a very simple trip that is split into two destinations so I used two routes rather than a stop in the middle as I know the middle destination point there is very hard to hit sometimes due probably to a map error. The first route starts with A and second starts with MA to keep the separated in the panel. This route is one that I have in the past done with drag and drop and for some reason it has real problems using the drag and drop that is probably related to very limited places to cross the river, so in this case even a simple route is easier adding the letters and hand selecting points. On a complicated route using the letters gets to be much more of a benefit as the route may have 50+ shaping points needed. With that many points, you don't know where you need to put the added one as the list is so long. If you click on any point in the left panel and then right click "show on map" you can see were it is. It may take a couple of tries to find the right one to where you want to add a point, but then you just letter it correctly and it is put in the list at the right point and is easy to know where to move it in the routing.
Here is a screenshot of the route with the first route showing on the map with the arrows showing direction. Second route is shown in smaller no arrows line.
This is with the route detail opened showing how it looks when done and changed to shaping points.
Linear Mode
