I read somewhere that she is at the 188 somewhere south of the Strip, but I haven't been able to find her. Thanks!

are you saying you can't find l88 trading post, or that you can't find veronica there

Just follow the main road north from Novac. You will pass a Scrapyard, then Helios power plant will be on your left, then 2km later there'll a gas station. Keep pushing north and a few hundred meters after that gas station you will see a small bridge above the road with some buses and stuff. Go up there, Veronica is standing next to railing and she will join you provided you don't have another main companion enlisted.

Awesome, thanks for the help.