Living in areas where salt is used during the winter is definitely challenging.
I use A product called Chassis Saver as the undercoat or just leave the item black or silver(color of the paint).
It is not cheap ! And one needs to keep from getting on yourself or where you do not want it. Also ! when it drys, between 2 parts, they are like welded together!
Kind of like a liquid metal.
It reacts to moisture(the catalyst)for it to start setting up. Do not poor any of it back into the can, The remaining paint will set up.
Put plastic wrap between the lid and the can before sealing it, or you will not get the lid off with out a struggle!
It wears off ones skin, will not wash off.