I've had this rig for awhile. the only places I could find rust is under the doors and I just found it under the trunk seal, mostly between the trunk hinges and corners. not bad really for a 27 year old car. might want to take a look before it gets out of hand. if not there it would be good.

 

After removing the seal I took a dremel with a grinding stone, a sanding attachment and ground and sanded all the loose rust off. used Ospho on the metal that had rust, after dry I used a rust inhibiting paint. on the spots that were rusted through the metal I used bondo resin with fiber glass matting and it worked well. after I finish the repair work I then used the resin to seal the trim all the way around. keep in mind it doesn't have to be pretty because seal completely covers it. I feel what may have cause the issue in the first place was the sealant they use to attach the seal. It may in the beginning been fine, but as a it aged it became dried out and crumbly which then absorbed water or maybe electrolysis. The most time consuming part of the repair was getting the old sealant out of the seal. I didn't see a reason as of yet for the sealant in the first place. so I didn't use it to re-attach. The seal seems to hold itself on well on it's own.