Chris.
I will say you should do your sump something like this. Have the first section about 14 inches long, with a baffle that goes up 14 inches. this will be your skimmer section. Then after that comes your fuge. You can leave the rest of the sump open for a nice large fuge, an dthe algae in the fuge will act as a bubble trap for your skimmer and drain. Then about 4 inches from the other end of the sump, put in a short solid baffle, about 3 inches tall, then use egg crate to go up to the top of the sump. The small section is your return section, and have it just large enough to get to your strainer to keep it clean. The large section is the fuge. the short solid baffle allows you to put sand/rubble if you want into the bottom of the fuge, with chaeto in the rest. It will work very well, allow you a large fuge, stop bubbles and give you the max space for drain back and evap without it causing bubbles with that large of a return pump.
Putting a frag setup in your sump does not really cause any problems when treating, since you treat the whole system, you would not try to isolate the sump from the system.
Kim