Wonder if you could rent a tank from a medical gas place.

I've kept fish and corals in a cooler for 2 days using an inverter powering a heater and powerhead. Might be an option for you.

50hrs for a cleaner shrimp and a neon goby in bags with oxygen for me...

I got a power inverter with 2 plugs. One for heater and one for a bubbler or powerhead. Let me know if you want to borrow it mang.