Cast Aluminum Flagpole Bracket - Mounting Hardware

I'm looking for a way to mount a flag pole bracket made of cast aluminum provided with mounting holes made to a #12 wood screw. That means an ~0.5" head diameter and a 0.22 (9/64") shank diameter.

I want to first mount the bracket on a 0.75" thick hardwood mounting board and then screw that to a post. This approach means I can either use a short #12 flat head wood screw or a 0.25" flat head machine screw with a nut and washer on the back side of the mounting board.

The rub is galvanic corrosion. Aluminum is the most active metal if metal fasteners of any other metal are used. I have been unable to find any aluminum screws of the appropriate size.

The Made in China bracket was supplied with inappropriately small, pan head stainless steel screws, a combination predestined to fail.

Does anyone know of a solution to this problem? Clearly the seller of the bracket did not try very hard.

thanks,
baumgrenze

Stainless steel screws against Aluminum is not that big of a deal - paint the connection.

To stop corrosion do one or all of the the following:

1) Eliminate the Oxygen at the dissimilar metal connection. (Paint, etc.).
2) Remove the electrical connection path (gasket, paint, isolate the parts electrically),
3) Minimize the galvanic potential difference between the two metals. (aluminum - aluminum, etc.)