You can certainly try but that's stretching the reservation hold quite a bit. I don't see any reason though why you can't make that reservation with your Hertz Gold account and then make a backup reservation as you suggested above outside your account. You could try to go to the Gold desk first and see if they'll allow you to pick up the original reservation, and if not could you just get on the regular line and try to pick up the other one and do the CDP swap and then have them apply your Gold number at the same time. Lots of ways to do this. You can also try to change your earlier res as the pickup time approaches as sometimes availability opens up. I wouldn't overthink this though. Just pick a plan and go with it.