Hi we fitted these mirrors to our 7 in place of the original mirrors but we found them absolutley useless you could not get decent vision at all with them,
Many years ago I had them fitted on the front wings,fenders,of a Sunbeam Rapier and they were reasonable if my memory is correct but on the doors,no good.
Not sure how best to make them watertight though,if you are going to fit them may be best to get a stainless steel set.
Cheers
Moe