If you mean your tow bar is not level because of the difference in height from the receiver to tow vehicle connections, each mfgr provides its own specs for how far out of level the bar can be. Go on their website and you should find the spec for your bar.
2002 Keystone Cougar 286, 8,400lbs loaded, pulled with a 2004 F150 Supercrew, 5.4, 3.73 gears. Retired and enjoying life
I don't know why the MFGs spec would differ. It has nothing to do w/ the TB IMO.
A TB should never be running downhill for the chance of the toad climbing "up and over" in a panic stop situation. But of course the toad braking system would come into play there also.
Specs I found showed TB to be between level, and 2" max uphill. Makes sense to me. I would never run a TB downhill for obvious reasons. But,....I don't run toad brakes either.
'01 31 ft Rexall Vision, Generac 5.5k, 1000 watt Honda, PD 9245 conv, 200 watts Solar, 400 watt inv, 2 12v batts, ammeters, led voltmeters all over the place, KingDome/sat, 2 Oly Cat heaters, and towing a Liberty, or a Lowe bass boat, or a Kawi Mule.