Found 2 options that I think will work for lighting the orb, and accommodating the limited space for hardware.
This one has a metal casing for the coin batteries, so I could just put a magnet on the backside of the steertube and it's good to go.
This one has a much finer wire, and it isn't bright white, so a lower profile. I prefer this wire setup to offset any clearance issues as well. However, the switch/battery pack is a bit more bulky and likely plastic. It still uses coin batteries, but it's going to be harder to blend into the frame. I've asked if they offer a different switch option, so we'll see.
This one has a metal casing for the coin batteries, so I could just put a magnet on the backside of the steertube and it's good to go.
This one has a much finer wire, and it isn't bright white, so a lower profile. I prefer this wire setup to offset any clearance issues as well. However, the switch/battery pack is a bit more bulky and likely plastic. It still uses coin batteries, but it's going to be harder to blend into the frame. I've asked if they offer a different switch option, so we'll see.