Here's what I did about 5 years ago that seems to have stabilized things.

On the outside of both rear window seals, I used some window sealant I picked up from Autozone. It's in a white tube next to the Ultra-Copper and blue silicone sealants. I don't recall the brand but it is a thin viscosity, silicone sealant that seeps into the the crevices between the old rubber seal and the metal body. I think I did two applications on my rear wagon side windows, tailgate window, and windshield. Don't go too heavy the first time because it is thin to penetrate well and will run out from one of the bottom window corners if you apply too much.

On the inside where the rust had actually made about a 1/2 in hole at the bottom corner of one of my windows, I used a wire brush to knock off the loose bubbled stuff. Then used an aerosol rust converter on the rusted spots. Using a spray tube I sprayed into the back side of the small hole to get the interior of the body frame and got the outside as well.

This seems to have stopped the rust in it's tracks. Wish I could say the same about the floorboards, rocker panels, hood.....

mormit
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02 S40 , 98 V70 T5 Koni FSDs, IPD swaybars and HD Endlinks, 85 245DL 278,000mi V15cam It takes a licking and keeps on ticking