My issue with the on board propane models is they really don't last long. When we boondock we stay for 6-10 hours with the genset running more or less the entire time. That would get me about a day on the miniscule propane tanks most rigs (even larger ones) come with. Sorry but I'm not filling my tanks every day or even every other day. If you boon dock so little that isn't an issue then you likely don't need to drop 5k+ on a built in to begin with.
We are getting ready to order a DRV and we are skipping gensets this time. Going to go the Honda route, bolt them down and run them from the trucks tank. Seems an inexpensive option and more flexible to boot.