I want to install and boarding ladder to the transon on my princecraft. the problem is there is no access to put bolt on the bottom on the ladder. The toop bolts will go through the transon and I can secure nuts in the splashwell. Any ideas? Can I just use screws for the bottom mounting bracket and bolts on top?

I would guess if you used thru bolts on top you'd be fine with screws in the bottom as long as they are of proper size. When your boat is on plane it will be out of the water, and when the ladder is in use there shouldn't be any outward force.