I like the idea of a 3 channel mixer with 2 tts, and ableton on the 3rd channel. Timing will be key, but it will be easy to setup with 2 laptops. Mix some minimal stuff or acapellas with the tts, and drop loops and samples with ableton.

You could always just sit on eachothers shoulders, throw a long trench coat on, and play as a giant. Then only 1 person has to mix while the other does the jesis pose to end all poses