Bought a relay, some fuses, inline fuse holders, and connectors today. The plan is to add a new circuit for the aux lighting, driven by the relay, straight off the battery, with the switch selecting whether the relay is on, off, or driven by the stock high beam circuit. But it's been drizzling all day and I was soaked when I got home, so I haven't installed anything yet.
I had my first monkey, too. She was pleased, after getting over the initial trepidation over riding in something that looks like it fell off a scrap truck.