AIO planning stages

[Sugar Magnolia]

I have another question about the AIO I am going to build and would like some advice on the overflow.

 

The plan is to partition the 5.5 gallon tank so that I have a section for running media, a section for chaeto and the return section. The return and macro section is easy enough, but which way should I do the overflow into the back? Do I want to just use a dremel and create vertical lines - aprox 1-1/2 long x 2" wide or should I drill a hole for a bulkhead and strainer?

Edited January 19, 2009 by Sugar Magnolia