Upvote:1
Sure, should be no problem. Here's a list of all the car rental companies operating near the SD airport (from the San Diego Airport website).
I had no problem finding a small car at Dollar for 3:30 today at ~$50/day.
Upvote:3
There's no rule against it.
A quick search on hertz.com revealed plenty of options left for today.
I would try to secure it online rather than at the desk.