I put HOB filters on the tank sides, not back which gives nice flow. Are these displays or purely holding tanks? Can make internal overflow boxes or matten filters easily for dirt cheap.Well yes, you could totally wimp out and just buy conventional HOB filters, and suffer the conventional problems.
Or you can build a wonderful super custom one-of-a-kind filter system, which is way more fun.
Not everybody can deal with this.
Also HOB filters, in my mind, are not ideal because they mostly provide cross tank circulation (unless you use a flow robbing diverter of some kind.)
I noticed that my fish are much happier when the flow goes in the long direction of the tank.