Very nice, what about rigging up some sort of low noise PC fan with an AC/DC power adapter and place the fans(s) behind the units in the back to move some air?
OK the scythe fan quiet types Amazon has them, even in slim versions.Gentle Typhoon is very quiet and should be a enough air, but there are others that are pretty quiet and move a little more air too.
And you will need something like this a Coolerguys 100-240v AC to 12 & 5v DC 4pin Molex 2A Power Adapter The fans are such that you can run them in series and run a lot since they are very low draw etc.
I did something like this for some parasound class amps I use to run and made a nice looking box and put a grill guard on the fans too.
OK search to for 120 mm fan grills,
Good luck, but this is a cheap small and quiet to do it.