I plan to leave the trailer hooked to the truck when raising the front. That's why I went with a jack with 5000 lb lift. I'm trying to keep the ramps short so they don't weigh more than I can handle by myself. It's hard to see what angle I'll have with the ramps until I get the trailer jack installed and can lift some. May end up using 2 X 10 treated boards braced on the back just for the weight factor.
I have two sets of ramps, my 4' steel car ramps and a set of 7or 8' wooden ramps. I will say if I use the car ramps, I can not load any tractor that has mower deck or hanging low implement as it will drag and hang up. I do sometimes jack up the front of the trailer while still attached to truck to help loading angle, sometimes you just park in that wierd spot where trailer rear sticks up too high even with long ramps. I just broke one of my 2x10's while loading my Sears 16/6 with snow blade. After plwoing snow, tractor slid sideways and off boards, rear axle landed dead on the board, broke it in half. Next set I build will have angle down both sides for bracing and some thin expanded metal or some types of cleats for traction.