Humming GFIC outlet

While boondocking, I would turn the inverter off when not in use.

It is connected to an inverter, so it has 110v output.
I don't use it much, and only for very small loads (e.g. recharging phone or computer). My main concern is drawing power from the battery even if not used, since I will not be "on the grid". I will take a spare with me.

Humming noise......loose connections or weak

Replace it.

Boondocking........you will only have 12V DC power from battery unless you have:
Generator to supply AC power OR an inverter connected to battery system to supply AC power (GFCI is AC).

Second the spare suggestion. Or just replace it.

You might want to have a spare on hand just in case although they can be purchased from any hardware store.

It won't be a problem unless you will be running that outlet from an inverter.