I've thought about doing this myself but, I just use my car's engine bay. It takes up less storage space and by the time I fabbed-up something, the materials and time weren't worth it for me.
Right, that's where I'm at. If I'm going to 'test' it, why stop at leaks? May as well go to dyno or just drop it on the mounts in the car. I think the biggest reason for me is the space it uses.