Mounted the strut brackets to the steel and fitted it to the fuselage.One concern I had was making sure the holes were lined up on both ends. Here's how I did it. First, I drew a line down the entire tube using a piece of scrap lumber.
Next, marked 1/2" from the end on both ends.
I measured the width of the tube and set up the drill press with a block that was exactly 1/2 the width. I carefully clamped the tube to the drill press using a cardboard box the support the other end.
Finally, I drilled the hole on both ends.