>>292018748
I think it's best to just delete the faces that are covered by clothes as much as possible. Good for optimization anyway since it reduces overdraw. If you don't want to do that for whatever reason, you may have better luck using the data transfer modifier to transfer weights from the body mesh to the clothes, which should match the weighting by nearest neighbor. Applying a subdivision modifier temporarily to the body mesh might help too, not sure what the state of the art for clothes fitting is these days.