Need plumbing help...marineland dd specific

I'm getting ready to plumb the drains on my 300 dd and I'm at a crossroads...



Do I use 2 of the bulkheads as designed and cut every other tooth out like I've seen done in other threads OR



Do I make all 4 bulkheads drains and still cut every other tooth out of the overflow box and run my returns over the top OR



Do I make both drains in 1 overflow then just 1 in the other and run my return through the 4th bulkhead and still cut out every other tooth



I already drilled 4 holes for closed loop pumps and really don't want to drill anymore plus I'll be doing maintenance from the back since it's in wall so a huge c2c along the back won't be very practical or else I would have drilled for one of those and removed the overflow boxes



So that's where I'm at and I need to use the overflow boxes for practicality so what do you think will be best??



Drain piping will all be 1 1/2" except the 1" bulkhead that marineland insists on putting in there so idk how much of a limiting factor it will be if the plumbing is up sized on both sides of it??



I don't want to do a full siphon because one noise isn't an issue since again it's in a wall and I'm afraid if the power goes out I'll lose siphon and have a flood which I obviously don't want!!



Thanks guys and gals!!



Stewie