Should I use rust converter on this?

[PranK]

One of the first jobs with the E39 is making sure the tailgate stays up. In BMW fashion they made a little cavity under the roof to hide the dampers rather than putting them down the side like everybody else. 

As you can see I have these little cavities that house the dampers. When I cleared one out and vacuumed as much crap as I could out of it I noticed a fair bit of rust. The cavity is bone dry, even after all that rain we had only a few days ago so I'm assuming that whatever allowed the moisture in is fixed but I'd like to treat the rust in there. 

I was thinking of just blasting it full of rust converter but I didn't know if this would be beneficial considering I can't actually get in there to prep anything. 

Maybe there's a better product? 

Thanks guys

[PranK]

Sorry the pictures suck. So hard to get camera and light in there