You could do worse than keeping an eye out for an Antec Veris A/V cooler like this one here:
https://www.ebay.co.uk/itm/ANTEC-Sou...AAAOSwqLFdZqn2
It sits on top of your item and its fans pull air up through the item, into the bottom of the cooler and then push it out of the rear of the cooler. I have one for big power amp use and it's quiet and effective.
I don't think they're made any more, so you'll be relying on secondhand.
Engineers: fixing problems you didn't know you had in ways you don't understand.