Good Luck.
We had the same desire when looking for ours a couple of years ago. No one then made a decent quality unit that was short. I guess there's not much market for a shorter length. We had a garage it had to fit into. We got pretty frustrated because of the limited availability, but also because manufacturers don't publish how long their units really are. Salesman won't help you because they don't want to go to the trouble to actually measure it. Don't take the published specs as gospel. Most of them list the hitch to bumper length. But you need to include the ladder and overhang in the front. Our overhang alone was 17".
We ended up with a Montana High Country at 33'9", but I wish I could have gone shorter. For the two of us, about two feet of that is wasted, mostly in the living area.
We camp a lot in NFS campgrounds also. We have been unable to get into approx 10% of the spaces we wanted because of length. However, many times the published limit online is shorter than what the campsite will allow (of course, you don't know that 'til you get there).
Artum Snowbird has a good suggestion. That unit was not available when we were looking.
Amateur Radio WA4GIY
2015 Montana High Country 305RL
2013 RAM 3500 4x4, crew cab, long bed, 6.7 CTD, Aisin trans.
CGVW 20460 Lbs.