overflow constantly breaking siphon

Well, an aqua lift pump is a good idea. Why would you even want to chance an overflow?

Also, on my setup if anything goes wrong all of the water in the sump can be pumped into the tank without overflowing and the lowest level the tank can drop to doesn't overflow my sump. I can't understand why more people don't design their system with that in mind.

 

I think you missed my sarcasm.

The problem with HOB overflows is that is the siphon breaks, the return pump- will flow over the tanks edges, because the overflow is not working when the U tube breaks siphon.
Yes, allowing extra room in the sump for the water to suction from the DT is how it should be done.
Yes, an aqualifter, or a powerhead with an air siphon tube hooked to the u tube is IMHO a necessity for HOB overflows.