Start in a big empty parking lot. Have them drive around, make turns, back up, get up to 20-25mph then slam on the brakes. Get the basics of how it handles at slow speeds so mistakes are less likely to be dangerous.
Then figure a nearby route maybe 10-20 miles long with light traffic and minimal hills. Take them along that route with you driving explaining what you are doing as you go. Then switch and have each of them drive it (yes, they should both learn).
Then being in Colorado, I assume you can find a moderately hilly area, so they can practice with grades and how to engine brake. Again, start with you driving and explaining followed by them taking a turn.
Being a toy hauler, make sure they have a toy or other weight in the back as they tend to be highly front loaded with an empty garage. You don't want them learning with a rig not set up properly.
By this point, they should have a decent idea of how it handles and from there practice will be their best learning tool.