I can attach it to the solar panel, or I can attach it near the battery box. My original thought was to put it in the box with the inverter/charger, and connect the batteries in that same location.

Hiya... thinking about a similar install on a 2008 210 Pop. Was thinking to put charge controller up in the left rear interior, then a jack down around the bumper for the panels to plug in, then hardwire controller to batts, but have not found a good path thru floor yet. Where are you putting your controller?