You could use a CCTV power supply like this: https://www.amazon.com/Monoprice-Channel-Camera-Power-Supply/dp/B0069MB6G0
They're not usually very rack friendly though, but they are 12v DC with plenty of channels and can usually handle a decent amount of power per channel, since they need to power IR LEDs on the cameras. You would just need to find or build pigtails with the correct size plugs for the converters.
Maybe consider getting a 12v camera supply, and install it somewhere closer, like a ceiling space. That’s what I did for a half-dozen cameras when the rack was going to be 200’ away. There’s a bunch on Amazon.
Something like this:
Monoprice 16 Channel CCTV Camera Power Supply - 12VDC - 10Amps https://www.amazon.com/dp/B0069MB6G0/ref=cm_sw_r_cp_api_i_gurhCbPSQ66FK
Depends on your needs but for me I also have a large number of 12v devices (cameras, switches, etc) and use something like this.
https://www.amazon.com/Monoprice-Channel-Camera-Power-Supply/dp/B0069MB6G0
On my rack, I have a bunch of Pis and other 3-5 volt things and so use a big USB multi power supply.
I just looked it up on Amazon for Prime Day...24% off. Thought this might help you save a small bit of change :)
https://www.amazon.com/Monoprice-Channel-Camera-Power-Supply/dp/B0069MB6G0
i went with one of these https://www.amazon.com/Monoprice-Channel-Camera-Power-Supply/dp/B0069MB6G0
when i outgrew 10amps i bought another power supply to replace it, but made sure it fit.