In my last attempt to remove bumper rust I used the coke and foil method with limited results, this time I went a bit further. I first sprayed the area down with WD-40 and let it sit for a minute then used a wire brush to remove any loose rust. I then applied rust removing gel to the area and let it do its magic for 5 minutes. I went back to the area and used the wire brush again with some additional WD-40 and it did seem to work well.
After a few treatments to the bad spots on the bumper it removed all the rust and left only the spots where the rust had eaten through the chrome. Overall it was a success and cleaned the the bulk of the bumpers rust. The odd thing is that while the rear bumper shows a lot of rust the front bumper is perfectly rust-free.