
Kadee 1-scale coupler on flat car. People glued to the platform with Dollar General hot glue.
The hot glue was an experiment. The people are stuck solid on the plastic platform, but the glue lets go when I push hard on them... perfect.
The Kadee coupler was an experiment also. It couples nicely with Lionel couplers. A body-mounted coupler on this long flatcar will not swing left and right far enough for O-27 curves. The car derails as it enters the curve from tangent track.
Here is a full-scale coupler for comparison to the 1-scale coupler.

Could those O-Gauge, 2-Rail, Model Railroading guys be using HO couplers and not know it?