I don't think anyone installs them anymore. They are still available. Reasons I can think of: Fire danger, CO danger, propane leak potential, lantern mantle replacement frequency, though they do have ruggedized lantern mantles these days, and heat output during hot summer months.
2003 GMC 2500HD 4X4 D/A Ext. Cab
Propane Powered Honda EU2000i
Lots of Hot Sauce!
Air # 283