Corrosion X
Whether in storage or actively flying, Corrosion X is an excellent corrosion inhibitor that can be applied in a fine mist spray across everything from bare metal to electronics. I spray my engines down as well with it after cleaning at each annual inspection and it works great, but then I do the whole aircraft internals (includes tail, wings and floorboards) every other annual.
Even for the folks who do prime everything, if you spray out your aircraft internals with C-X, or comparable product, you will prevent corrosion on all the other things that generally don't get primed, yet do corrode in time, such as connecting hardware, pulleys, control cables, wire terminals, etc...
Any excess application will evaporate over time, however, note that if you've not used it before, it gets into EVERYTHING and you will likely see black streaks coming from around rivets, seams and fittings - a pretty good sign that you had corrosion there, even though you may think it was secure with primer, and shows just how porous aircraft really are at a microscopic level.
Don't plan to paint for at least 6 months after applying it.