rust convertor, proofing, etc

[AbnMike]

My Disco is rust free, but I know there are some common areas prone to rust, and unfortunately the worst one (inside the wheelwell on the back passenger door frame at that crease) is the the one you can't see rusting until it's too far gone.

I generally, every time I wash it, spray up inside there as best I can from the wheelwell.

Is there any product I can use that would spray up in that area and rust convert (if there is rust, which you can't see) and proof it?

The pic is the area in question.

 

[bgbrox]

I did some research on this topic for spots under my LX470 (somehow my $500 D1 is rust free). Although POR-15 was talked about a lot, I went with Eastwood Black Rust Encapsulator - Paint Over Rust. They have a few products that you use depending on whether you will be covering rust only or rust and steel. I liked that it was one-step and seems to be well received by people who do more of this than I do.