I'm pretty picky when it comes to tank setups... so here's my advice.
Hang on the back filters, canister fills, all that hang on the back stuff... will get you by, as in generally keep your stuff alive. But it is my firm opinion that properly set up, thriving reef tanks, are all very similar in one extremely key factor: filtration.
A properly set up reef tank, and any saltwater tank for that matter, is a drilled tank, utilizing a sump for filtration. The first key is having your tank drilled, after all, when you buy a drilled tank from a store it's called "reef ready", if it's not drilled, it's not reef ready. Overflow boxes are big and bulky, and I don't care if you've had an overflow box for 45 years and it hasn't overflowed, it's still far more likely to stop working and spill water on the floor. I don't think anyone can argue with that. They're also more expensive.
Drill the tank for 1.5" bulkhead, just one will work, you can use an elbow and a strainer and be perfect. For filtration on the tank, simply buy a filter sock (like 12 bucks), and get a decent skimmer, ask around on brands before you purchase, on that size tank I'd get an aquaeuro or an octopus.... aquac urchins are great, but pricier and for no good reason. You can put macro algae in your sump, or pack it with live rock for more filtration. Nothing is better than liverock at filtering marine tanks.
For a return buy something cheap like a Via-Aqua, or one of sunlight supply's Eco pumps, and you're set.
A sump is not only going to allow you to have FAR more and BETTER options as far as protein skimming goes, but it will take all that junk like heaters, downtubes from filters, etc. and put it in your sump out of sight.
Also, reef tanks utilize high lighting, which is hot. Having a sump will act like a heatsink, and help to keep your tank cool.
I could ramble all day as to why you should drill and sump your tank instead of using hang on the back anything... but I'll spare you.