The flat panel style only stick to the fixture if the heat shield (aka reflector) in the fixture is flat. A lot of light fixtures I have seen are not flat in the top, so the flat circuit board style will not work.
That's why I went with the ones from
http://www.ledtrailerlights.comI actually happened to meet the owner today while wandering a local event where he was selling his product at. Very nice to chat with and share RV stories with. It's nice to put a face along with the name of a company now. :)
I've read other posts that mentioned him also owning an RV, and now I know he does, and he tests everything out to evaluate it's usefulness in a given application.