I had a 44' triple axle 5th wheel with the huge slides so it was very roomy inside. But I did have trouble finding nice RV sites for it on short notice. It was 15,700 or so empty and loaded up it was a bear in the mountains. Pin weight was was too much for a SRW truck. Down in Florida I always had to be extra careful to squeeze into those old campgrounds. I usually ended up at the more rustic places inland at monthly rates.
Had a heavy 40' Cedar Creek Day Dreamer that weighed 16K plus for full timing and it wasn't much fun pulling that weight in the mountains either. But it had less overhang and tandem axles that handled good.
I just don't enjoy pulling those heavy suckers long distance, I down sized to a much lighter mid rise 29' for occasional use and its tight inside but easy to move around. If I went back to full time I would stay around 35' or less OAL. I had a 9,800 dry 34'-4" OAL rig and that was a good size for moving around every couple weeks and easy on the truck. I probably should have kept it!