The passenger door window screen the OP posted can easily be made with simple inexpensive hardware nylon door screen material sewable with a sewing machine. All you have to do is measure, cut and sew a slip over sack.
Our new B came with screens. On the side sliding door we have a sliding screen door. I think Great West Van, Inc. is the only company that has solved this problem. Since we will be traveling with a cat we can leave the sliding door open and the screen closed when in the camp ground. The sliding screen door is on a spring that keeps it open and you close it manually to a latch. It is a pleated design similar to window blinds.
On the rear doors our dealer sold us this roll down and zipper screen enclosure. Great West Van had a different factory option that had to be taken down and put back up with snaps. The dealer's version was better.