I'm using a high solids copper/graphite grease on my st/st fasteners. Its got lots of conductive stuff in there but the thread which really suffered (on the side case frame clamp) has been no trouble ever since and it's been used all year around with an (un)fair share of salt spray.
My aluminium side cases develop more oxide fuzz up to 20mm from the st/st brackets which I assume is electrolytic corrosion. The bike gets used all years around so the cases can be wet overnight when I'm away from home and I don't have time to surgically clean them after every ride. What a shame the plastic protection sheet wasn't left on the alloy when the brackets were riveted on.
For plating stainless fasteners I would zinc plate the shanks only to leave the heads nice and shiny. That would protect the threads but have no effect on surface corrosion such as my side cases. Alternatively, have the original fasteners bright zinc plated to restore the original looks. There is the hassle of cleaning them but most plating kits have solutions for that.
Desperate times need desperate measures Always preferred the adventure but was a bit too fst and short, losing weight meant mylegs weren't so spread (oo er matron) so I could resch the floor easier.