My son is now almost 3.5 and our biggest hurdle was for him to be potty trained while not completely naked!
He still has occasional accidents, but is mostly doing great. I decided we had to take it in steps. First, I left him sans pants and he'd wet his underwear. We went through a LOT of underwear in a day, let me tell you! I also got advice from my pediatrician to not hurry to change him out of his wet underwear. Once it gets cold, they don't like it and start thinking that wetting their underwear isn't such a good idea. For this phase, he suggested I set aside a special day for it, block off an area of the house that has hard floors, move the potty seat to that area and make him play in that area all day until he gets it. I didn't actually try that (we never had a whole day to devote to it.)
I think what really helped my son may not work for you because of the time of year. He had swimming lessons this summer, and I put a reusable swim diaper on him. I told him that it doesn't hold in pee pee, so he needed to not go pee pee in it. I really didn't think it held in pee, because the disposables don't really. He had an hour every day that was special, that he REALLY had to remember not to go pee even though he was dressed. He only came home with pee in his swim diaper about 5 times all summer, and then after that he did so much better with underwear and pants.
I wish there were a handbook to tell you exactly what to do. I hope you get some ideas for what to try next!
