And I re-read your response, I will have a 12v car battery from the list (with solar too) and that will power the pump and fan. The link I provided is for USB hubs with step down designed to be plugged directly into a 12V battery. I got two of them and all the other stuff I want to use is all USB po...

The fan and pump will be direct wired as per the specs as I understand them (which I could be wrong), is the inverter used for anything else? It seems like everything will be powered from the battery and the inverter is just there to provide power to other devices? Or am I confused?

I'm building out the figjam cooler and was considering not getting an inverter and just powering everything off of USB which should be much more efficient as it's DC to DC. I'm buying these USB Step Down Converter: https://a.co/d/2GTcUNv Anyone already try this? Any gotchas or problems people see wi...