Richard, I found that once I had the wheels chocked and front jacks down just enough to almost unload the truck I put the truck in reverse (auto trans) with engine idling, it will take the tension off the latch. I did it just this Tuesday and purposely ...since this thread... checked if it would unlatch and latch using just my little finger on my right hand.
Almost couldn't but it came! When I went to hook up it hooked up again no problem. I didn't measure how much the front was lower but I will guess at least a foot. The hitch plate on the truck rocked back was nearly parallel with the pin box capture plate and the tailgate was nearly hitting the underside of the fifth wheel.