Drill a siphon break in your return lines?

[Hustler]

LOL i was reading that right after i clicked post... didnt make much sense still having first coffee
My return bulkheads are below the level for my overflow so my display will drain about 2" to the bottom of those bulkheads... this is what im trying to avoid as its like 80 gallons or so.

So if i were to drill a hole at the top of the elbow behing that bulkhead it would stop at the top of the bulkhead?