All:
Forget about waterproofing altogether!  We just weathered a torrential
downpour with NO LEAKS anywhere.  OK, the windshield leaked, but that's
another story.  The canvas got wet, but nothing came in anywhere.  We're
talking Wizard of Oz, 40 days/nights (Hi Ken!) rain and wind that lasted for
several hours, after a day of drizzle and light rainfall.  Everything was
damp from the 100% humidity, but no rain came in.  The canvas performed
exactly as it should have.  No need to waterproof as far as I can tell.  Of
course, Your Results May Vary!

Doug
84 Westy, 83K