... looks like the AV Infinity fan is too small for this unit.
Do you mean the AC Infinity component fans? If so, I think you’d be surprised. The top exhaust full size 17-inch models will move 210 CFM and the rear exhaust units move 160 CFM. You might want to compare that to whatever else you’re considering. I use a a rear exhaust fan on a tube preamp that fits rather tightly in the rack. It’s a great solution. I think Audio Advisor sells them, so you’d have 30 days to try one.