How to avoid Galvonic Corrosion?

[Prop]

I intend to fit an aluminium awning rail to the side of our l2h2 ducato van for a drive away awning.
I intend to fix it using adhesive and a nut and countersunk screw fixing.
After seeing and fixing the corrosion behind our st. stl. side door runner I was wondering what material fixing bolts to use for this and do I need to put a spacer such as a fibre washer between the rail and the van body and maybe the screw head and the aluminium.
Any suggestions gratefully received.

 

[AdrianChen]

On our aluminium boat mast, steel fittings used Duralac for isolation. Some fittings (not under any great load) had gaskets, but all the fasteners were seated with duralac, even of they were mad from Monel. I would avoid anything that will absorb water and hold onto it - Stainless can start to get crevice corrosion if held in relatively oxygen free water, but that may not be a big risk in this case.

 

[Orion]

I’ve always used Duralac compound when joining dissimilar metals. Available on Amazon but possibly less expensive elsewhere if you search:

https://www.amazon.co.uk/dp/B084618BYY?tag=mhf04-21

 

[Jabstatt]

Duralac all the way. And try to avoid any voids where water may accumulate.
Avoid salt water like the plague.

Tony