" I was extremely concerned about the cancer risk and was surprised to come across this in the wikipedia article on sunburn:"

This sounds like you're reading the article incorrectly perhaps? The sunscreen isn't causing DNA damage in and of itself, it prevents one form of severe harm and leaves others intact. Don't go in the sun unclothed if you want to avoid cancer.

"Now I'm left with one more dilemma"

It's not a dilemma. It's always a bad idea to get long exposures of sunlight if you can avoid it.