As mentioned, forget the chain tensioner.

However, a fixed cog (on the correct chain line) with a freewheel outboard should work. The trick will be to have enough movement in the dropouts to tension the chain properly. However, I suspect the real deal breaker will be the number of threads, you'll need to make sure you have enough threads for the freewheel to be happy.

Obviously, you won't have an adequate locking ring to support skidding, so it's brakes all the way, which is what you need for SS anyway.

Worth looking at. Please report on your experiments and discoveries. There's a reason flip flop hubs have become popular.