RE: Westies in the rain
Wrong list Mike, you should post this on the WetWesties list.
That said these precautions help (but don't cure) some of the problems you
mentioned.
An awning extended a couple of feet outside the slider creates a 'rain
porch' that will minimize the tracking in of mud, etc.  And a good rubber
door mat, on the ground, outside the door, under that rain porch, will also
give you a place to wipe your feet before coming in.
If you have the top up, in moderate rain, you will get much less rain on the
canvas than you might expect.  But it will get damp even wet in some spots.
If you have the time before putting the top down, run the engine to generate
heat, close the doors and windows and turn the heater on full blast, fan
going full blast.  You reduce the amount of moisture remaining in the canvas
that way.  Then remember when you get home to pop the top the first day you
have no rain, get it dried out.
Rubber boots especially if you are going to be where it will get muddy.
Leave 'em outside, under the rain porch.
And anything you stash under the van to keep dry will get wet, guaranteed...