Hi, Joe.
There are a couple of possibilities here.
First, you could just set your trace interval low enough so your cellular gateway never goes to sleep. That's the easiest solution for this. You can play around a bit with trace intervals until you get one that keeps the cellular link awake all the time (maybe 15 seconds instead of 5 minutes).
A second option, if you're using PingPlotter Pro, is to use a script we built a couple years ago for someone that sends out a single (unlogged) ping to the final destination, then waits a bit (1 second in the current version, but it could be upped a bit to match what you need), and then it sends out the full trace request, giving the cellular link time to wake up. This script may have some issues, but a quick review makes me think it should do what you want.
If you're interested in getting this script, shoot us an email at support@pingplotter.com and reference this thread and we'll be happy to send a copy over to you (with the appropriate warnings, of course).
- Pete