Seems to me the same things that make FGRV an attractive choice for camping, namely compact, sturdy, well built, lite weight
would also make it attractive for commercial operations.
Link a little while ago on the forum to a 16ft converted to a dog grooming service. This guy rents bolers out and uses one at trade shows as his booth. The Happier Camper
He invented the iBallz protector for tablets. iBallz Original
I personally would not take a nice sharp original classic and gut it, or really do a whole lot to modify it. Taking one that is in need of TLC or repair and giving it a new lease on life seems cool.
In the end a mod is a mod is a mod. Does not really matter the purpose of the mod. Only who might want pictures posted so they can do it too.
Lots of folks cut holes and put in AC, some folks would not want to cut into a "classic". I think in the end it's their trailer so it's their choice.