Seems I mis-understood the original problem. You meant when your trailer is higher than you TV sloping up. I stayed in a few sites like that, where my trailer tires were 1-1.5 FT above my TV rear tire if you drew a straight level line. When I had a TT here is what I did.
Get into position for the site and lined up on level ground. Dis-engage the bars and sway control. Now the rear is sagging a bit but unhitching is easier since I don't have to crank up the TV and TT to ease the pressure off the bars. Now position the TT in the site and check for side to side level only.
Once I got it level chock the wheels, get back in the TV and while holding down the brake pedal shift to N then back to P. Now release the brake and the TV usually will move about 1-2" and set my TT in the chocks and eleviate the pressure on the ball. Now I position the blocks and raise the front of the TT. If the ball hangs up I repeat the process with the brake. I have found that if you release the brake while doing this the TV will move 3-4" and pull on the front of the hitch too much.
I used x-chocks after getting the unit level front to back as a double measure. You should not use them until the unit is completely level. It will damage your axels as you raise or lower the unit.
If your in the opposite situation where the TT is lower than the TV then the boards usually will get you close enough but check your tension on the bars on level ground again as the pressure will increase as the units level out.
2014 375 BHFS Eagle Premier
2014 Ram 3500 Longhorn DRW CC
6.7 CTD, Aisin, 4.10's