Any exterior screw that the head is exposed on, needs to be backed out halfway and sealed. That includes ones on the bottoms of the inside of cargo door openings. The way to do it is to buy a tube of Proflex RV caulk, and put a dab the size of a pencil eraser on the threads of each screw, then just screw it back in. It will end up under the head of the screw.
Besides the cargo openings, you will find them on the ladder mounts, on many of the things attached to the sides of the MH, and maybe even on the roof, believe it or not.
You might see that some of your windows or other side items have a thin bead of caulk across the tops and partway down the sides. Or even all the way around. This is good! However they don't always do every item. Like say the fridge or water heater flanges. So, if they didn't do every item, do the ones they didn't!
Go up on your roof. Make sure the Dicor lap sealant looks good on all the things up there. Do that 2x a year. If you ever see any cracks, clean the area and dribble some new lap sealant over it.
OK, that is probably not what you were looking for, but if you do those things, and they are easy, your RV will last a long time, body-wise.