I've had a problem since buying my car, but it's one of many. Rather then tackle all rust issues and whether to consider panels used vs. bondo, etc.

Everytime I filled my tank, as seemingly careful as I tried, something made it down the side of the fender from the fill hole. Over the years of owning it led to at least one rust spot above the wheel well I can't account for. The tank may be partially loose, but rather then deal with the brackets, when I tackled my fuel pump, I opted to go in the trunk from the top.
My suspension needs work so may replace rusted bolts/brackets at that time, but wondering if this sounds like THE probable cause?

Any similar experiences, I'd like to hear. I never had the car detailed but regular cleaning of gas streaks proved quite difficult for me...this is on white paint where it can't help but show up too
BILL S.