At some point, you are going to have to use the cloth room for this methinks.

You can either use a conforming piece you have saved as an OBJ or you can use a piece of conforming clothing.

Either way, you need to release all of the constrained groups. If you don't they will retain the figure shape even laying on the floor.

Be sure to check the "cloth self collision" box when you set up the simulation.

Set ground as the collider.

Set fold resistance to "1" and sheer resistance to 10."

Run it.

Wiser heads than mine may have a better solution, but this typically works well enough for me.