I stand corrected… You also need an electrolyte to cause the reaction…so, the sweat (salt water) from @Troll’s hands as he pulls Gs in a dogfight would provide that…actually just casual touches of the steel-aluminum joint would cause it, not to mention the sea air of @Troll’s domicile.
So yes, as you indicated, the aluminum will suffer galvanic corrosion just from being bolted to the steel.
However, I found this solution on line:
So how do you avoid galvanic corrosion? You electrically insulate the aluminum from the steel. The best way to do this is to use bolts and nuts to make the joint. Use an isolating coating or paint on the aluminum and the steel to isolate them electrically. However, all of your effort will go for nothing if you just bolt the joint together. You must isolate the bolt and nut from the aluminum and steel. You do this by putting a nonconducting plastic washer between the bolt head and one side of the joint and another nonconducting washer between the nut and the other side of the joint. If the pieces being bolted are thick enough, you should also buy a nonconducting sleeve to fit on the shaft of the bolt to keep it from making contact with the steel or aluminum. Thefabricator.com.
…all things considered, he’s probably better off making an aluminum stand…or rebuilding the entire thing in steel.