K.C.
If he loves to be naked then the deal should be no pooping outside. If he poops outside I would put his clothes on immediately and maybe even take it away for the next day if you think he understands that. I would also go over the rules at the beginning of outside naked play and even pause in the middle to take himto the bathroom. I had a similar pee issue with my 3 yr old when he was playing video games (he wouldn't stop to go pee so he just peed on the computer chair). 2 days with no computer helped him stop that! Good luck!
K.