Ahhhh Mr X, At last, something we agree on!
Drilling a tank is easy!
About the drill press (pillar drill) whatever the title!
I used a wooden jig and a hose feed for coolant (water)
I was working on sheet not a tank but it could be done on a tank, you'll just need some kind of tray to catch coolant.
Just offer slight force toward the jigged corner and it prevents wandering.
Nice holes, all on a line.
You can do it one handed and take pictures!