Bill
If you will have access to and enough room behind (beside?) the tank at the end you could drill the sides and put the durso stand pipes on the outside of the tank. Then you could build smaller overflow boxes on the inside of the tank,saving space and also have surface skimming. Hope that made sense. I'm still trying to picture how to do it myself as I type this.
If you want to drill the bottom and don't want to put an overflow all the way across the end of the tank (then you would have to hide the part you could see into the overflow from the side) you could make a u shaped (3 sided) overflow box and put it in the middle of the end. I can bend the acrylic for you if you want. Or you could get fancy and put a 4 sided overflow in the middle of the tank.
I would use big bulkheads. It's easier to restrict the flow if the bulkhead is too big, than it is to increase flow if it is too small.
I like the idea mentioned of drilling a hole for an extra bulkhead you can always plug it if it is not needed or use it to plumb a return from the sump.