You can carry a few spare spokes taped/ziptied along tubes or inside the seatpost. Or if you really want you can braze some spoke holder on the non-drive chainstay

It's good to carry some, especially if you carry large loads on bumpy terrain with low spoke count (less than 32; however you can get away with a deep section rim). It's better to have some and not using them than the contrary. Make sure you know how to true a wheel.

For the drive side use the fiberfix or the hypercracker (nice tool btw, anybody used it?)

edit: do you guys think the fiberfix works as well as a steel spoke under torque loads? I guess yes when properly tensioned...