Load my sled in my truck all the time (2014 Ram 2500 4x4 short box with a leveling kit and 34" tires).
No problems with a 7' ramp. I also used to ride my snowbike in all the time as well.
Now if I had a 6" lift and 37s I wouldn't want to do it without a longer ramp
Make sure your ramp has plywood or glides were the skis run and open rungs for the track to grab. It also helps to ditch the carbide runners and get hardweld replacements. Also, its nice to strap the ramp down to your receiver hitch so the ramps don't push off. Watch how the ramp lays on the tailgate. If it has a "C" shaped support, it can be pain to get the ramp out with the sled on it. That is how my bifold ramp is. I took the hinge off so I have two separate ramps and can slide the ramp to one side to remove each ramp. If it is just a flat piece that rests on the tailgate, that makes life easier, although it comes off easier, especially in reverse.
I leave the tailgate down unless I need to tow a trailer with a short tongue.
As long as your sled has reverse its easy pesy. Snow bike is more of a pain.