Chain Tug on converted road frame

There you go. Perfectly executed.

BMX chain tensioners

I've used these before and they worked fine.
You have to file down the relief part that normally sits in a rear facing drop out though. It took all of about two minutes and then you have a strong, cheap, though ugly tensioner. I would say though that they are quite thick so you have to have a bit of extra length on the axle (I was using Goldtecs which are bolt on so that matters less)