the ideal way to treat these panel is to first alodine them. This starts the corrsion process through chemical conversion. Then once the dwell time is complete wash off the alodine and prime and pain. The otherr way is to use a zinc based primer then cover with the color of your choice. The best way to keep galvanic corrosion down is to set up a schedule where you remove the panels clean them up and represerve. You can use a silicone based sealant as long as there is not an acid in it. Look at Home Depot in the rain gutter section. They sell acid free silicone for the aluminum gutters. Using a gasket will only prevent the two metals from rubbing causing fretting. Another option is to use a corrosion inhibitor and wet seat them. There is a product which is made from lanolin called "Fluid Film" which is what I have used on the helicopters I worked on. Great product and repells water really well. Also soften your hands. Preventive maintenance will be your best option. In the high salt climate you are in I would recommend removing them after each winter to clean treat and preserve as needed. If you see bubbles under the paint this is also a sign of corrosion espcially if you see white or grey powder.
Here is the site for fluid film
http://www.fluid-film.com/
Hope this helps,
Will