rkkwan

First, do not assume the later flights have lots of empty seats. Chances are the flight will be completely packed.

Second, I don't think you can get $25 confirmed standby on the later flight, as it's 5 hours later. You can only do it within 3 hours of that flight.

So, your only choice is a non-confirmed walkup standby, which can be very extremely risky, of course.