Indeed the dryer outlet is the NEMA 10-30. My plan is to get a NEMA 14-50 adapter, and a NEMA 14-50 50' RV cable, then somehow find an adapter to 14-30 or 10-30. Then I realized this is a BAD IDEA because the Tesla adapter is going to set a charging limit far above the capacity of the 30 amp wall outlet! So I think the (likely) 10-30 extension and adapter is gonna be it. However.....
I see your idea, interesting. I could get 60-ish miles while there then hit the SC on the way out of town. I think that's an OK plan. After all, it takes 25% more time to get anywhere "distant" by Tesla compared to ICE.
I'll write back when I decide. Thank you for the info.