I had what I think is the same workflow concept that C2 would be a quick and simple way to explore and develop a moderately simplistic version of gameplay concepts and mechanics while fleshing it out in 3d using Unity.... (unless this is meant to be a Unity 2d, but same idea in general).
Yes it does mean a dual build, but each has its advantage and what you can knock out quickly in C2 can be refined and developed more intently while already having worked out some of the gameplay do's and don'ts ahead of time.
Good luck with it!