Always good to be safe, especially when trying to figure out power loads! I know an electrician who has run A/Cs (both portable and window unit) off of extension cords until he could get around to grounding an outlet. You could probably get away with something even like 10 feet if you have to.

It’s a 12 gauge wire, so it should be able to handle it (they can handle devices with higher amps than that.) I have run a portable A/C off of a similar extension cord (albeit much longer) while grounding outlets in a hot room before without issues.

Waffles is a true warrior and a hero

They tend to be pretty LGBTQ friendly in the Seattle USPS branch, especially the letter carriers.