I have the Jensen -- it is equally as bad of a head unit -- but none the less I would be surprised if the iRV support anything but RCA. Might be worth pulling and seeing if there is an HDMI.
How much is the TV mount and Installation? If you are looking at a $500 TV, $25 mount and < $100 installation and you don't have to mess with it, I would probably let them monkey with it. If its a $250 TV and the balance is mount and TV I would do it myself.
2007 Chevy Duramax LMM/Allison
2012 Jay Flight 29QBH
2012 Jay Flight 26BH (Sold)