We've had 3 motorhomes over the past 15 years (assorted other campers before that). Right before the first motorhome, we had a trailer and needed a heavy duty truck to pull it. That left us having to use the truck for driving around when we were parked in an area for a while. We like having a smaller car to tow behind our motorhome, much more economical for driving around. Our motorhome is 36' and has slides in the living room and bedroom. Since we live in this all winter, the slides make it very liveable. If we were to get another motorhome, I would want one with 2 slides in the living area, as well as one in the bedroom.
For quilting, I keep my sewing machine in its case under the dining table and an assortment of sewing supplies in one of the large drawers beneath a bench seat at the dining table. I also have room for a large plastic drawer in the bedroom for fabric storage. I like using the 2 gallon zip-loc bags for making project "kits", and try to include anything I would need for each project (fabric, thread, any fusible or other notions and pattern.) This does take a bit of pre-planning, but its worth it to have everything you might need to use with you. I try to have some applique or other hand work to do as well as machine work. I have a folding sewing table (with an adjustable platform so my machine sits level with the table surface) that I can set up and use when I have a day when I can keep sewing. Don't forget a small ironing board and a travel iron works well. Keeping your cutting mat and quilting stencils under the mattress keeps them protected and handy. Most beds have space under the bed platform for storing larger projects. (Again, I like to keep these items in larger zip-top bags to keep them clean.)
If you spend any length of time in one area during your travels, many RV parks have craft/sewing/quilting groups, just make sure your DH has something to keep him occupied too. Living in a confined space can get old quickly at times, guess we're doing OK since we're gone from Nov. to April every winter!! Enjoy the RV lifestyle!!