I did my trip June/July from East Coast to LA.
I did use ORE code(this one worked for me the best), I also signed up for EC member of National.
I used Emerald Aisle so I just showed confirmation of reservation, driving license, CC at the gate at the exit.
Noone asked about ID with this Corporate Code.
Even I had to go back on the same day to the rental place, to fix my contract becouse guy at the gate added some extras to my rental that I didn't wanted( I have noticed that already in the hotel room) and they couldnt fix it over a phone, so I had to go back to airport and go to the counter and work it out with a MOD of National Car Rental.