You should know a little bit since you've looked at so many. That gives you an edge over internet shoppers.
Anyway, make a list of must-haves, would-like-to haves, like-to- avoids, etc.
When you look, lay on the bed, sit on the toilet-can you close the door of the bathroom? Is the shower big enough? Pretend to use the kitchen. Can you get to the bathroom with the slide in, (so you can use the facility on the road). How is outside storage-can you bring all your stuff?
The most important thing-Can you pull it? and will it fit in your driveway?
Bring a camera and notebook, start collecting info on possibilities.
Don't give up, you will find it! See ya done the road!