Wiring is the reason why I have not brought a dyno powered taillight with me when I traveled with my S&S bike. Instead there are two battery powered taillights on the back, one is mostly for backup purposes although in fog or heavy overcast I will run both. One of my taillights died from corrosion from frequent rain on one of my bike tours, I was glad I had two on the bike.

My wires from the hub to the headlight are permanently zip tied to the fork blade, the SP or Shimano quick connect at one end and 2.8mm spade connectors at the other end of the wires. That short run of wiring is so simple that it is a non-issue, only takes a couple seconds to connect the wires. I do not recall the gauge wire, I think it is 22 gauge. I used two separate wires, twisted together and then zip tied to the fork. That wire is robust enough that it would be hard to break in a crash.

You cited weight as a concern, weight of an SP hub instead of a plain (non-dyno) hub is pretty close to insignificant. I suspect that the weight of battery power for a headlight on a 1200k would weigh more than a SP hub. Thus, dyno powered headlight might be the lightest option.

A backup headlight could be quite light weight and probably would not have to have a very good beam if you have a really reliable dyno powered headlight system.

Bad things can happen. On a cold day I did not take my glove off, when I tried to pull the SP or Shimano connector off the hub, I accidentally pulled the wire out of the connector while the connector stayed attached to the hub because I did not have a good grip with my winter glove. I will be more careful next time. Nothing is totally accident proof.