As far as towing goes, I've owned an 18 foot, a 31 footer and now a 35 footer. I've not had any problems at all towing any of these.
Here's an easy "accommodation" that might fit your needs. More and more manufactures are using the rear double slide (on both sides) of the rear of the camper. And the furniture is stand-alone furniture, (not built in), which means it can be removed, replaced, or tossed out completely. If you looking for a camper so you don't have to remodel, one like this is a good option for you.
Below is the floor plan of my Outback. We did not get the dinette, we got a free-standing table and 4 chairs in ours. The couch is completely free standing and the two recliners can be put anywhere. We took out 2 kitchen table chairs and turned the table long-ways (parallel to the window), and switch the sofa and 2 rocker chairs locations. This provided a LOT more room when the slides are in.
But, we could remove all of that and have a wide open space. This is a good option. My camper is an Keystone Outback, but like I said, many of the manufactures now have similar floor plans.
Bottom line: Toss out that couch, or toss out the rocker chairs, or toss out the table, and you've got room for your desk.
EDIT: nice thing about this camper is, it's 100% functional with all the slides IN, especially since we switch positions for the 2 rocker chairs and the couch and turned the table and took out 2 kitchen chairs. All the cabinets are accessible with slides in, except one small one on the living room side of the kitchen sink. There are 2 drawers there, but even those can be opened with the slide in.
When selecting your camper.... take the time to pull all the slides IN and sit in the camper a while, check out the cabinets, and see how functional it is with everything buttoned up. There are occasions when you cannot extend the slides and you still need full access to everything. Just something to consider:
Slides IN. Imagine one of the 3 spaces with your desk. It would still be accessible even with the slides IN.