Typically at LAS, passengers wait for pickup at designated curbside pickup areas. Whether T1 or T3, the columns in these areas have numbers on them. So if you want to have your girlfriend pick you up in this area, head out to curbside pickup and tell her the terminal and number of the column you are at, and then all she has to do is look for the column number (a lot easier than looking for an individual passenger).

If you want to make it as easy as possible on her, have her park in short term parking and then have her tell you where she is. Then you go find her. Then she doesn't have to drive around at all; she just has to park at the right terminal.

That's not correct - there is a designated curbside pickup area at both T1 and T3. Cars picking up pax do not have to go into short term parking. As per the link you posted, what is not allowed is cars waiting for passengers in this area.