At Sikorsky and Collins we pretty much use shielded wire for everything. May be overkill for our application, but for the strobes I'd recommend shielded wire. Terminate the shield to ground on one end, whatever your grounds are in the airplane inside the cockpit.
One of the challenges we face is that the lock ring that holds the tailbeacon in place is designed for a vertical trailing edge. The Waiex trailing edges of the tips are not vertical. We were going to use the supplied aluminum lock ring and fair it into the tail, but having the mounting screws verti...
There is usually more than one way to skin the proverbial cat. Do a dry run with clecoes or a couple of aluminum pops and see if there are issues. I did not have any problems with those flush rivets.