You tank and filter setup are prime for an ATS[Algae turf scrubber] or two . They would help way more then a fuge IMO
As far as a fuge that should be easy also .
You just need eggcrate to build containment areas to keep the macros in place.My cheato just sits in constant flow with a light. Like for the ATS your lighting could all be hooked up to back of tank and not even be seen.. The flow is there as the water will naturally travel at a pretty quick rate depending on pumps used to return. You will have no head pressure or loss with the filter and return being level to tank.
I just make my water up in a brute garbage can and pump it in to my tank.
I have a pump in my sump I use to pump water out into another brute can.
Not sure the canister filter idea is worth it but would probably work.
If you are plumbing any pump /canister into the filter you will be limited as to how much water you can pull before it does not overflow into filter,so maybe a canister plumbed to tank will be a reasonable operating feature at least for removing water.
You have to prep salt water 24 hours in advance so you will have a can and pump already .Maybe the canister will work best for adding that water ,I just use pump and hose to fill my sump.