I am a big fan of the Loctite Extend rust neutralizer and have recently won Ray over to it too. The spray's great for getting into unreachable crooks and nannies, and they make a liquid form that goes on a lot like Turtle Wax. We were using that on the Sun machine last night with good results.
My neighbor just used this on a frame similar to yours and I was impressed with the results. You stick the 2ft tube nozzle in and draw it out as you spray. One step and done. Internal Frame Coating Aerosol Black 14oz