Projection onto tracked sphere

I have a thing coming up where spheres floating in a river (tethered but bobbing/moving around) need to be projected onto. I was considering CVTools but I'm looking for any suggestions, QC or otherwise, on the most reliable way to do this. Obviously factors such as this are worthy of consideration:

-Sphere's won't move drastically, or particularly quickly. -Potential video input as source(graphics, but a bit of an unknown) -Night time (fairly obvious), middle of river is approximately 20-30m away, so a decent lens required -Single system per sphere is possible. -If the cost of a "box" type solution (coolux etc) will discount the development time then please suggest if you know it's capable.

I'd love to hear if someone has done something similar with CVtools, or knows of something better. Cheers.