Hmm, not an expert, however plenty of experience showing up at starting lines undertrained, overtapered, and fighting injury.
Assuming your half marathon goal is to finish, I'd do the 10 miles in a jolly fashion, practice drinking and having gel or whatever else you plan on ingesting during the race. Then, maybe a nice equally jolly 3 miles on Sunday. Don't push the 10 miles. I think the payoff psychologically of knowing you can do 10 miles is worth it. Then just make sure you don't do too much next week before the race.
re lighting I like the idea of having something around my waist (and maybe the handheld) instead of a headlamp - I'll look to see if I can rig a headlamp that way. There are some fancy and $$ waist lights,
but I'm on a budget these days.