I'm not sure how you're going to deal with bunks. As I'm sure you're aware, the walls of any RV are quite flimsy, and unless you know exactly where the main supports are you might be getting into trouble by adding something that you're expecting to support quite a bit of weight.
If you've got someone who can do that kind of construction I'll look forward to seeing the pictures. As far as upholstery, since you're near a large city is there a garment district where you can buy large quantities of fabric at discount prices? I go to downtown L.A. to buy stuff like that. I think you'll be surprised at the prices and types of fabric you can find if you've got somewhere like that.
Laura -- and Jed