California - SJC Car Rental Center - After Hours Return Possible?

I have a reservation with Dollar and Thrify (one will be canceled, depending upon what I learn) at SJC. While I intended to drop off in the middle of the afternoon, plans have changed and I intend to move up to the 06:20am US flight back to Phoenix.

The trouble is that the Dollar and Thrify sites indicate their respective rental offices don't open until 6am, though the SJC website indicates 5:30am. Do they have an after hours return drop box and parking availability if they're not open by 5:30? Even that's pushing my comfort level. Would I be better off paying more for Avis which is listed on Avis as opening at 5am?

Why not call the SJC desks and ask? It can't be that expensive to call SJC from PHX and they may offer options that are not on their website or known to the national res #.

I could call but figured each agency has its own policy and making multiple calls is tedious. First hand experience of FT'ers often trumps what any phone rep or local clerk will tell me.

Additionally, if I don't get any useful info here, I figured I would inquire when I pick up my car. It's not a complete impossibility for me to drop the car off the night before and take shuttles / taxis from my silicon valley hotel either.