Given you've said picking up at SFO is the most convenient, I'd suggest...

Do a 1-day (or longer, depending on whatever is most convenient), 1-way rental from the airport to a local HLE. If you pick a return location nearby to the airport (eg, San Bruno) then you will normally avoid any one-way fees.

Then do a longer booking from that HLE for the rest of the period you need the car.

When you get to the airport, pick whatever you want from the lot. The next day (or a few days later), "return" the vehicle to the HLE, and ask to re-rent the same vehicle for the longer rental.

This will get you the lower rates/taxes for most of your rental, but with the convenience of picking up from the airport, and being able to pick your own car.

I've done this type of thing (with the return/re-rent) multiple times and never had them say no to letting me keep the same car.