My previous TT with a Dometic absorption fridge's manual said no more than 3 degrees from level. Our new TT says something similar to yours - comfortably level. Like you, our driveway is sloped and when I tried to run the fridge in the new TT at about 4.5 degrees (front to back) the fridge never cooled down. Now we pull the TT out into the street in front of the house and can get the level at about 2 degrees.
No issues cooling things down with that set up. I also bought
one of these battery operated fridge fans. It seems to cut the cool down time in half and I've been using it for a years worth of camping on the original batteries. As bikendan stated, we leave the fridge run while we're driving to the CG so between the precooling in the street and the trip, we're at a good temp by the time we pull into the CG.