Maybe try calling Hertz, from my brief googling it looks like they do special rates for UK citizens who are staying more than 28 days. I also saw Travel Jigsaw which was quoting lower http://www.carhire3000.com/Traveljigsaw/
I'm excited you are staying in my hood! A new Arlo's location is opening on South First next weekend! Let's plan tubing too, and see if we can figure out how to do a mega VVC trip.