When I get a blowing rain water comes in the top of the door and runs down and back out,witch is ok as long as the bed clothes are not touching the door.
I dont know what it is called but it is like a small roof over the door and windows.
I think your thinking of a drip rail/molding/cap etc. There are a few different types. One looks like a little "J" channel and the other is like a small metal awning. Here is a link to Lil'Bear teardrops where both are sold...
Not on a camper, but i did drip edges on a shed with doors facing north. I made the door myself and was concerned with water seeping in during storms. All i did, I cut the top trim at a 45 degree angle and inserted a piece of `Z`flashing from HD. works very well for my application. Hope it helps photos showing details.
Shed details here: http://smg.photobucket.com/albums/v378/ ... 1QQtppZZ20