Avoid pickups at arrivals altogether especially in the evening and get picked up at departures instead. There are few evening departures from Austin, so the upstairs departures level is mostly empty.
And this is permitted, too. Electronic signs beneath the names of airline names in front of the terminal read “DROP OFF PICKUP ONLY.” The airport officially encourages upstairs pickups! I’ve also never had an Uber driver refuse an upstairs pickup. You have to specify a pickup location at arrivals, but I then immediately send a pickup message asking for upstairs pickup. The driver almost always thanks me (and this is probably why my Uber rating has climbed to nearly 4.9).