Blue Ox allows 3" height difference, that puts you at the limit, but O.K. Best situation is to have both points equal. Tow vehicle low, toad high in an extreme emergency stop could cause Jeep to 'leapfrog' up into the back of the RV. Having brakes in toad reduces this chance. The only other option would be mounting a 3" drop bar upside down, raising RV receiver to be level with Jeep base plate. Problem with a drop bar is they 'weaken' the rating of the receiver because of the angle pull.
Honestly, I wouldn't worry about it. I had a drop receiver to make my toad/RV set up perfectly level, but I was gouging almost every driveway and cross street gutter. I took it off and live with a 2" difference in height. (and I also use auxiliary brakes in toad)
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI