I put one in my Taho in 2000. It was on Onan 3800. It was an easy install. Spliced into the coach propane line. Put an outlet box by where the land line cord was stored. Had to get a new door for the compartment with vents and cut out the bottom. Added the remote start so I would not have to go outside to start and stop. All in all it was about $3200 for the whole thing, but I did it all.
2012 GMC 3500HD 4x4
2009 XLR 40X12
2009 RZR ready for the trail
Days camped in '14 - 63
Days camped in '15 - 96
Days camped in '16 - 74
Been discussed here before - some of the issues discussed were exhaust routing, inlet for air,sound inside and sound proofing, fire detection and suppression,reinforcing the floor,the possible need for additional propane supply,and if there's room for it.
I don't recall anyone ever doing it,but perhaps some people did.