Well if you find something good that isn't rubberized for the wheel wells, please post back here as I don't have a solution i like. I don't do rubberized as i moved from a place where i saw how much rust it hid and allowed to grow.
So Eastwood has some cavity spray and so does KBS coatings. They come with a tube and a diffuser nozzle that is nearly Omni directional for getting in to various places. I am using Eastwoods version.
Also you might look at something like rp-342 or the CRC equivalent. Is durable and you would...