Make or have made a drill jig that slaps onto the side of the 2x6.
Hold it in place with a couple (maybe one) vise-grip setup clamps.
Get a hand full of 12" drill (or 8" if you can find them www.Mcmaster or
shorten the 12" ones for convenience.)
Use a Milwaukee 1/2" HoleShooter & go to town.
Using a such a drill & a really sweet drill jig I was able to drill 25ea 7/16"
thru 1" aluminum is about 1/2 hr.
Since you've got 1200 holes to drill cycle time is key unless you want to spend
forever doing it.
With a jig it's "no fuss" just set jig & drill............next hole