The Prindle 18-2 and Supercat 17 both use 'boards. The Nacra 5.7M and Prindle 18 are boardless, with the Nacra being a skeg boat and the Prindle being asymmetrical. Of those two, I'd go with the Nacra 5.7M because they are still being produced.

You won't be able to right any of them single-handed (without modifications) unless you're a very large man. Adding righting pole should allow you to right any of these boats single-handed.

Since you do not give your location, I'm not sure which odd-ball boats might be in your area that would better suit your needs. For instance- a G-Cat 5.0 (~16') or 5.7 (~18') are boardless, dual-trampoline boats with both the room and buoyancy to carry 4-6 people comfortably without undue loss of performance.

I've had 9 people aboard my G-Cat 5.7M in 15knots of wind and 4-6' rolling seas and a good time was had by all