Potty Training Blues

My son is so strong willed that if he doesn't want to do something, he isn't going to do it. Potty training is one of them. He is almost fully trained to go #2 in the potty, but he refuses to wear undies and refuses to pee. ((sigh)) We have literally tried everything!!! Nothing works. Treats, stickers, happy dances....nothing! We have bought him his favorite undies...Spongebob! No go. I have tried just not putting diapers on him, but he has meltdowns. He hates being naked, weird, I know! He likes the feel of diapers, he says. What can I do?!?! NOTHING?!?! HELP!!!!!!!!