Sump Design Question

I am redesigning the sump for my new 120g tank. The previous ran a fuge on the right side of the sump and I don't use a fuge, so... I am debating between a two or three chamber sump. First section drain, second section skimmer/ heater/ probes, third section return/ ATO. Or just having a drain/ skimmer and then a return. My question is on the baffle height. My skimmer needs to be in 6" of water. I have the following sections of glass that I removed from the sump. One 6" piece, One 7" piece, one 8" piece and 2 12" pieces. Using the three chamber design, which baffles determine water height? Figuring that the drain section will be- over/under/over baffles into the skimmer section then over under into the return section. How do I maintain a 6" water level in the drain section?



I hope this makes sense to yall....