Julie,
you know, I think that David Ramey has said this frequently on this forum: it isn't necessarily the skills we lack; it's the marketing. Ren is a very competent photographer. But he's no more competent than you or Dee Dee or James or many of the rest of us. What he's done is create a great marketing concept. Instead of trying to drive a finite number of local people with pets into his studio, he's decided that the entire country is his market and he goes to them. With a rolling billboard. Very clever.
He's clearly made a commitment to his business in terms of investment: bus, people, time away from home. But he's executing a very sound marketing plan and probably making a pretty good living by doing so.
Think about it: given your life and your lifestyle, could you really do what he's doing? Not many of us could. A nomadic marketing concept isn't something many of us could afford to execute if we have a home, children, family and other things tying us to a particular location. In that regard, he's fairly unique. But he's doing something we'd all like to try. Honestly, haven't you just fantasized about traveling around the country photographing pets and making decent money?
Maybe we can't do it quite the way Ren is but the concept of expanding the market by being willing to go out to it is a valid one. At least you have an RV! My mobile marketing facility is a GMC van

.
Still, the concept is tantalizing. . .
Jim