I've already got one sideline business... and it's ruined one hobby. Not making that mistake again!
Seriously, not that it's a mistake. My little sideline has paid for several vacations, all of my flight training and flying, and now it's paying for the RV. You do have a valid point, Henning -- built RVs are going for pretty good money.
I suspect, though, that it would work out to less than minimum wage.
On the bright side, as I work on the RV I also plan to drill out the pop rivets and screws I used to attach the floor runner strips on the '55 Vespa, and replace them with real rivets. You just can't get everything to sit right and stay snug otherwise.