RTB is already both client and server sided, and both client and server would need to have RTB for the prop system to work anyways.
So I don't see how it wouldn't be able to work.
Ephi also mentioned some stuff about looking into automated previews a while back, so that could help in making it look all neat.
Should the system be constrained to single builds? I know for a fact people will often put a bunch of random bricks just outside their builds for either testing, as a toolbox for stuff to be duplicated in, or just for screwing around. The reason I wonder this is because it would be pretty neat if we could get some system in place where you select a save to load and get to load it somewhat similar to how props are planned, except the placer just sets down one big baseplate ghost brick with the x/y dimensions of the build's footprint. Then you could position that and load the build wherever you want. With the right stuff uploaded, a player could create an entire city in 30 minutes.
