Getting a frame with a broken right dropout and having a set of horizontal dropouts that's what I did..
30 years ago..
I could braze , do metalworking, and had built a frame from scratch with modest access to tools , , assistance and materials.. ..
Yes a spring-loaded chain tension-er is good ... I have 2 IGH bikes doing that..

You aren't, unstated , wanting to do another fixie conversion ?
....