I think you'd be happier with the larger unit.
The difference in the lengths when driving on the road is not much. I'm far more concerned with and aware of the width and height of my class C than the fact that it's 32' long. If the front fits somewhere, the rest will follow along obediently. Naturally any of these will not accelerate, brake, or corner like a car, and so driving conservatively and watching the road a lot further ahead are necessary.
Length does make some difference when maneuvering around gas pumps and camp sites and parking lots and things like that. None of the motorhomes you're looking at are really good for tight maneuvers, to be honest. There are very few if any vehicles that have a worse turning radius than a large class C motorhome on a stretched van chassis.
Getting out and looking over the situation before proceeding in tight maneuvers is an exxcellent idea...as frequently as needed, even if it's every couple of feet. It's far better for other campers or drivers to suspect you're a cautious newbie than to go crunch against something and prove your an incautious one.
Deploying people in your party to act as spotters is also a good idea. Make sure you have an understanding of what they're looking at and how you're communicating. Sometimes the most useful is to have no communication other than "STOP NOW," at least from all but one key guide. Also make sure the spotters are watching both the top and the bottom of the motorhome for hazards.