Thanks for the reply, John. That probably is the most simple (inexpensive) solution, and will be the most likely one I land on.
I think there is a set of Ultegra downtube shifters at my parents' house. Easiest thing to do would be to get those and mount them on the DT, but I'd like to keep everything up on the handlebars.
Has anyone here ever used the Paul Comp barend-to-thumbshifter converters? Are they: 1. worth the cost 2. compatable with Ultegra DT shifters?
Or, I could just go find a used set of friction shifters on eBay.