Backing a 5th wheel up a Steep Driveway

I have a similar situation. I had to back in at an angle to avoid hitting the back receiver. I was less than an inch of clearance. I have a 38' 5th wheel. The big things would be ground clearance at rear of unit and the overhang from the back axle to the bumper. If that measurement is short enough it will start coming up before it drags. I wouldn't think the overall length would matter much as the rear overhang. I am not concerned with the axles loading and unloading as it hits the transition. Your going slow enough that its not much different than going up on leveling blocks.

Unless your good with geometry and have exact measurement the best way would be to try it out. You could compare the trailers your looking at to your friends for measurements. Just go slow and watch all your clearances.