That might be pushing it. Riding out to the ranch, riding all day and then riding back that evening.
You'll probably be pretty tired and not on top of your game heading back into Austin.
I one dayed it last year, but I trucked the commute portion.
I left long before the butt crack of dawn to get up there in time to head out on the Saturday ride. I didn't get home till midnight.
If you can swing it, I would try to at least stay overnight one night. Either come up the night before and head back the next afternoon after the riding. Or leave early in the morning to get out there, do some riding then chill for the evening spend the night and head back the next morning.
Besides, that'll give you some socializing time. (read drink beer)
If you are free though, hook up with everyone meeting in Austin Thursday night, or Friday morning head out and spend the weekend. I don't know if any of the cabins still have/need another person, but if not I am bringing an extra air mattress you could call dibs on. I am sure someone will offer some floor space.
Don't worry about not knowing anyone.
I am a total introvert. I showed up last year not knowing a single person, and these folks welcomed me right in.
