I'm currently holding a Budget reservation in Las Vegas for 2 days at $42 all-in, with a 3rd day for $32 all-in. Currently, to book 3 consecutive days is over $150, so I'm more than willing to trek back to the CRC to re-rent the car. But of course it would be ideal if I didn't have to.

What do you think my success rate would be at the counter to have these 2 res combined at the lower rates ($74 total)?

What do you think my success rate would be if I CALLED before the expiration of day 2 and asked to keep the car for another day (not mentioning my other reservation?). Do you think it would be for a reasonable $20-$30 upcharge or a ridiculous $110 or so more?

All were booked through Costco.

Any personal experiences?

And yes we need a car in Vegas since we're doing lots of things where a car would be helpful.