Glass question

[WDLV]

I'm working on a project whereby I will need to remove a large section of glass from an existing aquarium. Visualize the false walls occasionally used for external overflows. The current plan is to use a hole saw to drill the four corners of this hole then use a Dreml with diamond wheels to complete the perimeter. This is on 3/8" glass.
Is there a better way that does not involve disassembling the aquarium?

I don't want to discuss the project itself. That will be revealed after completion.