Oh, that's a bummer. (About the GPS, that is.) I had a similar problem on my last long run before the Marine Corps Marathon. I was on travel for work, had scoped out a course online but didn't know the area at all, and had to run 20 miles. My GPS never synched and my iPhone battery was so bad that it was under 50% by mile 5. Blech. Still don't know exactly how far or what pace I ran. At least you've run a night race before W&D, even if it wasn't the best. You've got a better idea how to prepare and you're still in good shape since you've been doing some running. If you're concerned about pacing, you could go low tech. Cool Running has a
pace calculator tool. Enter the time and distance and it gives you a target pace. Then click on the link that says "Calculate Splits". It gives you a desired time for each mile. Write the biggies (i.e. 4, 6, 8, 12) on your arm in Sharpie (I told you it was low tech) and glance down when you hit that marker. You can adjust faster or slower from there. I used it in conjunction with my watch so that even if I dropped GPS due to tunnels or bridges, I had a time to check. This was the first race I did that with and I think I'll do it all the time now, it kind of lowered my stress level to see in ink that I was on track.