Haha! They did a few crossovers in the 80's, but only single episode narratives that played out on Sesamstraße, and not on Sesame Street. So, working on a crossover would be a dream come true! It was a little like it for the 40th anniversary episode, with Ernie, Bert, Cookie and Grover here with us though.
But so far I'm really just an occasional puppeteer for silent background or one-line characters on the show, as all the main characters have been cast. But who knows, maybe one day... :)
Hey, would you mind if we made you a wiki page? Peter Savieri has one, and I think you being on Sesamstrasse (even for background stuff) counts. But I wanted to ask you in case you were concerned about privacy.