Clothing Optional?

Lately we have really been working with Evan on getting himself dressed and undressed. He loves zipping things and gets upset if we do it for him. The problem is that he is applying this new knowledge when we don't want him to! At Toni's house the other day she went to get him from his afternoon nap and found him with his clothes off and half his diaper off too. Yesterday afternoon when he woke up from his nap he was talking like he normally does, but then he was crying and seemed very upset. I went into his room and found him with his shirt halfway off, but he somehow managed to get one arm into the neck hole and was completely stuck in the shirt. Then this morning I went in to get him and he had his arms out of his pajamas and couldn't figure out what to do next. I'm just worried about him getting his diaper off and making a mess. I've heard of people wrapping tape around their child's diaper so they can't take it off... Maybe that's not such a bad idea!