Hey, what's wrong with the Nacra 500 to sail single handed ?
The Hobie Wave is a total different league than the Nacra 500. The Wave is more or less a toy-boat, you'd better consider the Hobie Max or the Getaway. FX-One is also a probability, very good one-up and easy to rig for two.
I've never sailed the Hobie 17 Sport, dunno if it is ok for singled handed sailing ? Please leave the geriatric seats... ;-)