Decided to drill my tank

[Easto]

I was thinking about drilling near the Middle of the overflow Box height. Then putting the siphon tube with the elbow facing down. I haven't measured but I'd think that would give 1.5" - 2" between the siphon and the bottom of the box, which sounds like it's fine.

The second one I'd drill at the same height but turn the elbow up facing.

[CM125]

I would try to get more space then that, even if you add some pipe on the top or bottom, it will fluctuate a lot in the beginning and its nice to have that extra. since you have the option I would definitely do it.