This is what I am starting with.

The stand has two storage spaces where I have 2 canister filters right now.
They measure 16L x 20W x 19H so I am kind of limited on how much I can put in and I will probably have to custom make what ever I use but I am open to suggestions. If I want to do a FOWLR would I need a sump? Protein skimmer? I really just want a few O. clowns, a tang, and a few other fish, I just dont want to overstock it. I already have a 4 bulb T5 light; I will be ditching the two canisters and should I keep the HOB. What filter would you recommend?
I guess I am really just looking for an economical way to convert it. I know there is nothing economical about this hobby but there is also ways to go about it so you dont break the bank.
Here is my old reef!!!! It was a 40G breeder.

Thanks in advance for the replies.