I would try a good pair or running shorts. Like the ones you see people that actually go running for several miles at a time wear. I have a pair I wore under a costume for a musical. they literally stop half way to my knee and come up higher when I sit. Those might work. Or try wearing something like leggings that are spandex. wearing something like that under shorts might give your thong lines some definition. I'm assuming you want people to tell what you are wearing without actually revealing that you are wearing a thong. Keep us updated on what you picked up.
