To quote Dave Nadler, "How hard could it be?"

Love the quote. I'm thinking this might actually be pretty easy to do as a modification to an existing glider with a FES configuration. Most of them already have two batteries and it would be simple to add a second motor controller. The hard part would be mounting the second sustainer motor in a clean manner. I'd have to do some structural analysis, but it might be possible to add a motor to the vertical stabilizer. Alternatively, one could glass motor mounts onto the wings for a pair of 5kW motors.