Kenny.... It may be fairly common. You've gotten several responses here, and in my case I have an 8 in rise from my MH receiver to the tow bar height. I have the 8 in adapter (received with the coach) but this adapter has an extra long receiver shaft to bring it out to clear the coach bumper. As an earlier poster commented, an extension like this will reduce allowable tongue weight but will have little effect on gross tow weight when you're flat towing.
John & Diane, fulltiming since '12
'02 DS, FL, Cat, '04 Element
John & Diane, Fulltimers. RVM103 NHSO
On the road since June '12 with Lincoln, the guard cat.
2002 Dutch Star 40, Freightliner, Cat 3126, 2004 Element