Mamba™ driveshaft system (using "Bevelheads" and Universal Joints from Lewmar)
Yes, the forward rudder is vulnerable... Designing it to survive a heavy blow (or fail gracefully) is challenging but not impossible. Carrying a spare is a good idea too!
Whichever rudder is loaded most heavily will be moved the least, requiring some kind of "collective", or independent setting, as described for Tom Blackaller's radical canard ruddered USA-61 and refined later by DynaYacht, now CBTF Co..