This comes up every once in a while. I used to have a great photo of a strongback that featured wheels mounted on one end so it could be moved wheelbarrow style, but have been unable to relocate it the last couple times. Oh well. In any case, the answer is: of course you can add wheels, just remember that your boat is only going to end up as straight and true as the mold upon which it was fashioned, so take pains to see that all forms stay in alignment at all times.

But then, making sure that all forms stay in alignment at all times is a good idea whether you pull a wheelie with your strongback or not.

One other thought: in telescope making, the mantra is "three points define a plane". In the case of a movable strongback, it might be well to add one "tongue" footer to the end opposite the wheels, to form a tripod, to reduce tendency introduce twist on different surfaces. But I don't know, tripods often sound like a great idea but don't quite work. There's good reason why tables usually have four legs, cars have four wheels, etc.