I think you may be out of luck on that one, but still worth some investigation. The sofa is in the slide out which is raised over the main floor level to clear the wheel tubs (at least that is what the pictures appear to look like to me). I would expect that the raised level of the platform would have to remain to clear your wheels, and the mechanicals for the slide are probably down there too, putting a stock chair too high.
You might get a better idea by looking at it from the outside with the slide-out extended.
ETA: If possible, you might consider cutting down the legs on some existing furniture to get the right height though!
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2012 Chev Traverse LT with TP