That is a truly nice vehicle, and it is a shame that rust has begun to
attack it. Clearly, the shown rust began elswhere other than in the desert.
Most of it looks typical, and in the same quantities as many east coast
Vanagons.

I suppose deciding to actually do something about it is a difficult
decision. When that can O worms is opened more rust will be found. For the
windshield, you got to remove it. Not hard to do! With the window out more
channel rust will then show itself. This rust is most often seen on the
windshield and rear window. Often together. Want to take them out too? Most
likely rust is there in the form of rust holes. Got to either fill them with
brazing rod or POR15 Por Patch.

The seams are another matter. Got to gouge, gouge, gouge that seam caulk and
grind away at the rust. What a mess you will  make of the finish.

You get the picture. A big job not to be taken lightly! How about a whole
van repaint considering that all panels have some rust? Still, the rust can,
and most often does, come back unless done right.

I would learn  to love that rust in some way. Kinda like character, that
rust can be. Maybe fix some of it. Primer spots can have charm. First thing
to do is to reseal the utility boxes, as they are where water enters and the
Westy rust begins. Much of the visible rust can be minimized by using auto
polish and wax. Polish off the rust stains and wax over the rust spot often.

New Hampshire will be brutal. Perhaps trade vehicles and get a better desert
example while you are down there. It is much easier to keep a Westy nice
than it is to bring one up to better standards.

Good luck!