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.
--2005 Ford F350 Lariat Crewcab 6.0, 4x4, 3.73 rear
--2016 Montana 3711FL, 40'
--2014 Wildcat 327CK, 38' SOLD
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' Rexall Vision, Generac 5.5k, 1000 watt Honda, PD 9245 conv, 300 watts Solar, 150 watt inv, 2 12v batts, ammeters, led voltmeters all over the place, KingDome/sat, 2 Oly Cat heaters, and towing a 2012 Liberty, Lowe bass boat, or a Kawi Mule.