You need a boroscope to look into sills and stuff to see how its constructed .. it can be complicated with hidden box sections within
this is a transit connect sill
download/file.php?id=38373&mode=view and this is what the sill turns into near the front wing .. the slab of metal is what i put in to make a a stronger jacking point.the rest is just copied from original
download/file.php?id=39055&mode=view never used lanogaurd .. so don't know
i can tell you what NOT to use
any bitumen based product including products named: the old type of shultz , bitumen underseal, bitumen paint, tar etc, as they will dry out in 5 years cracking and letting water under the coating, so promoting rust, not stopping it.
all the best.mark