Look around for a rust preventative spray, a friend of mine sell some that can be washed off then painted later. Also the powder shop should clean and pre bake your part so call them and ask if coating the parts with a light coat of oil or what ever they recomend.
Go to http://www.oilcenter.com/
They have a product called MD50 that I put on my 5th wheel hitch because it was always rusting. I put it on and it stayes outside and it has not rusted in a year now. It can be washed off and the part painted.