Use Boatlife Marine Silicone. Works good and is marine grade silicone, not household stuff. Much easier than the 3M to remove. We have if you need.
I second the vote for Boatlife - Life Caulk.
It's tough as hell to get off but not as hard as 5200. 5200 is the wrong product, if you're trying to seal something, IMO. It's a marine adhesive and does an amazing job but I wouldn't use it on anything I might have to take apart later. At least with 4200 you can heat it and get it to release by pounding the crap out of it. 5200 is pretty severe.