Steep Boat Ramp

With a Lance 865 in the bed of a 2012 short wheel base f250 4x4 crew I am wondering how steep of a boat launch ramp is too steep to turn around on. Some of our lakes draw way down and due to the lines, backing down the side while waiting isn't an option. You need to turn around at the bottom! Of the ramp.

Any guess what the max cross slope a truck with a truck camper can reasonably handle and not get light weight on the up hill side. Of course the turn will be made nice and S L O W.

Thanks,

Rob