Bill the power supplies you have been running what kind of load were they running?
If you are only pulling a few amps then its not going to create much heat.
I am intending on running about 1500 nodes and the power supply will be running at about 80% load, 48amps on a 60amp PSU.
I think I am going to mount 2 hubs in a c1500, one on each side when open, then running the atx connector to one board and drive connectors to the other board.
As for the PSU it looks like I am leaning to a large storage tote with the PSU inside and hoping the airspace inside is large enough to not overheat the PSU.
Something else I have considered is a cheap fan pulling air through a heat exchanger/tubing so that the expensive PSU is not exposed to sucking moisture. I much rather replace a cheap fan than an $80 PSU.
By the way I'm in South Florida and so I am more concerned with heat, not too many days here below 32F.