Would it not help to have both an abundance of live rock and a hob filter. I dont see why a hang on the back filter is not useful
I have a 65g with a HOB FLUVAL C4. HOB REEF OCTOPUS BH1000.
What works for my 65g is the Marine Pure plate I put in the chemical media basket. Also the 62lbs of good live rock. My ammonia, nitrites, and nitrates are always 0ppm. I feed 2-3x a day heavy.
Get yourself 90lbs of dry rock with high porosity. Get it clean for a good month or two with heated saltwater and a powerhead. Do 100% water changes every week.
Get the FLUVAL C4 stick a plate of Marine Pure in the media basket.
Get a REEF OCTOPUS BH 2000 or Classic 90.
Get an AQUEON PRO 200W
Get 2x Jebao OW-25 wave makers.
Get an LED light that does not have the ability to support algae growth or corals.
Get a sand of choice. With the depth you want.
If you really want to beef up the filtration. Add a 2nd C4 and do the same by adding another MP plate.
This is about as cheap as you will get in my opinion and have great results.
A lot fish will be great for a tank this size, but I would look for fish in the "30-75g suggested requirement"
If you are thinking of a tang. Tomni would be your best bet. There is a bunch dwarf angels that could work. Look to add them last. There is some great wrasse to be had in a tank this size. Stay away from the 6 line. Marine Betta is a great idea. Small puffers. You could get a bunch of Anthias, just make sure they are fed enough times throughout the day(meaning 2x minimal).
If you are looking to add a media to the system. Get a HOB Tetra 10. Pick up some BRS ROX.08 Carbon. Make your own bags. You can also mix some Phosguard in the carbon to help with phosphates. Purigen is also another good chemical media that you don't need to change out for awhile. Says to change every 6 month.