This isn't really an answer to your specific question, but I have thought about this problem when daydreaming about rv-ing with our two cats. One of ours is a door-dasher, so I understand your problem.
I haven't done it, because my door-dashing cat is older and will never adjust to rv-ing. However, I thought that the way to do it if I could would be to get a "bunkhouse" model trailer, and convert the bunks into cat "jails." It would be a simple matter to use something like the snaps you described, or velcro, and some kind of netting to keep the cats in the bunk area. You could even build a stowable ramp if the bunk is up too high for the cat to jump up and down.
Setting up and breaking down would be a lot easier than what you described.
Then, when you plan to go out, put the cat in jail. When you are in the trailer and sure you're not going out, the cat can come out of jail.
You would have to be aware of not letting temperatures get too hot inside the trailer when you're gone and the cat is inside, but you would probably be doing that anyway.
A drawback to this idea is that there may not be many bunkhouse model trailers that you could tow with an SUV. Lance comes to mind; they have a smaller, lighter bunkhouse model I believe.
My $.02.
2005 Rockwood 2104
2011 Toyota Tundra SR5 5.7L 4WD
Equalizer
Prodigy