Hee, imagining Lisa scribbling like mad in her notebook. Almost a Muppetism in itself.
As for that cameo reference... Got a few guesses.
1 Denver, the city Robin's in. You chose that as a subtle connection to John Denver? Especially since the whole gist of his TMS episode was that they'd go camping with him... Which they eventually did in a Rocky Mountain Holiday? And that's the center focus of your story, Robin camping out in the Rocky Mountains and just now made it to the city of Denver?
2 Mrs. Thomas... The fact she's named Thomas, a reference to the newest
Forget anything left of 2 above.
2 Larry... Perhaps Larry Block who portrayed the human character named Tom on Sesame Street?