Unless you're clean out of the water, I'm not sure the loads will be so high since the unit has it's own buoyancy.
Although lots of pics on here and in magazines have folk showing off with their boats out of the water, if you drive properly you may find you rarely get into that situation.
I don't understand the oo-ing and ahh-ing that folk do when they see a boat out of the water, and therefore out of control, with it's bow 3mtrs into the air. Kinda like doing handbrake turns in yer car.
Perhaps I'm too old to know.