I just got the Jackery 300. Fully charged I only used 20% of the battery to run one 7 hour night. This was with the humidifier off. I purchased this DC power supply for the unit which also saved battery.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I will probably use this method for a bit until I either install another inverted outlet or just run an extension cord from the inverted outlet in the bedroom. I agree that they should have made a different outlet inverted in the bedroom