I was experimenting with making lowpoly assets on one UV map using stacking and because you cant use baking on stacked meshes in painter ( at least i dont know way, well beside adding UV-s later, i make short Tutorial /my Experience modeling my one pic i found on net old Pannonia house around 7100 quads (no interior) i…
For this question: "because you cant use baking on stacked meshes " Do you mean stacked maps? I'd just do the classic approach of moving the stacked UVs except for one out of the way by 1 unit (or -1) and then just moving them back when you're done texturing the one.