Hmmm - you may find thongs less restricting. It also avoids panty lines. OK, OK, just kidding, most lifters would sympathize with your situation.
In the winter, I wear these stretchy running pants (kinda like yoga pants) in my unheated garage, they always fit and add a little compression also (I only turn the heater on when I'm in it, but it takes a long time to reach temperature in the 50s Nov-March), but I'll check out the shorts you suggest for the summer.