I’ve had a little time to come up with a more elegant solution than a reconfigured 7 speed freewheel. This time I cut the non drive side threaded section off a bottom bracket shell for use as a coupler. Inside that goes a non drive side cup from a three piece square taper bottom bracket. It all threads together and aligns the chain line properly. The non drive side cup from a sealed square taper bottom bracket may be used as well. This solution works on wheels like this which you cannot adjust for dish, as you could with a standard spoked wheel.
Bonus photo of a suicide fixed gear set up with a bottom bracket lock ring (which I do not entirely recommend).
by JPHarlock