Thanks for all of your contributions everyone. I'm learning a lot. The most significant thing to learn is that the trend now seems to be stepping away from canister filters. That's interesting considering the stores I've been too (including aquarium specialty stores) all say to use cannister filters.

There are a few immediate implications to not using canister filters that I am unsure of (eg. without mechanical filtration, what's going to take away the dust and carpet fibers that inevitably lands in the tank?), but I'll start a thread about all of this in a few days when I've read through more of the guides that Canreef refers to.

If not using a sump, were you planning on using a hang on skimmer? If you are worried about water polishing you could add a phosban reactor to run carbon in a forced manner.

Do you have any pictures of the spot you were planning on using the cannister? Could you have a small "ish" sump built to fit the space?