i say this every year, but people fail to absorb it into their brains.

1)rear lower hatch corner rust-
 the #1 cause of your rear hatch rusting out in the bottom lower corners is
because the factory puts these stupid black plastic plugs in the drain holes
therfore the drains wont drain...   open your hatch.  look up at the 2 bottom
corners.   remove those round plastic plugs.    DO IT.   dont stand under it
when you remove the plugs otherwise youll get a faceful of water or
dirt....proving my point.

2)westy seam rust on drivers side horizontal seam under fill ports-
the #1 cause of the horizontal seam rust on the drivers side westy rocker
seam - and in worst case scenarios right thru the side panel directly under the
fill ports - is because your fill ports are leaking.

20 years ago, when your vanagon was shipped to Weidenbruck to
Westfalia-Werke's factory to be made into a camper, they just cut 3 square holes in the
drivers side panel, applied a foam gasket, and screwed the fill ports down.   thats
it.

20 years later, this foam gasket has long been reduced to dust, and everytime
it rains or you wash your van, water leaks in around the perimeter of these
fill ports..soaking the fiberglass insulation behind your kitchen unit and
never drying out.. water takes the path of least resistance to escape, so it seeps
thru the drivers rocker seam, and breaks thru to the ouside leaving rust in
its path..
there is also a horizontal body beam on the dirvers side panel just below the
fill ports,  and water often sits and festers on this beam, saturated in the
insulation, and rots holes right thru the side of the van where this interior
beam is..

anyway.. easy way to prevent water from getting in is to CAULK THE PERIMETER
OF YOUR WESTY FILL PORTS. its easy. DO IT.  regular exterior grade household
caulk will do.  take 5 minutes max.  one tube of caulk costs 5 bucks.

drivers side sheetmetal replacement takes days or weeks or months in a
bodyshop, and costs hundreds of dollars.

you decide which is easier.

ps, i have parted out many westys..and i have never seen ONE that did not
have any drivers seam/or inner floor rust because the fill ports were leaking.
what?  you dont see any seam rust yet?   you will.   your ports are leaking
and you dont even know it.  i could pull your sink stove unit and show you the
rust on any westy..it might not have made its way to the outer seam yet, but
it will.

i have sold westy interiors to people who retrofit their passengers vans with
them, and advise them not to cut the westy fill ports into the side of their
vans as its a source of rust.

chris