Hey Dan-
Two things. First of all, I learned on this very forum that you'll get noticeably better fuel economy at higher altitudes, which means you can expect to do better at 9000 feet than I do at 90!
The second thing, and I know you're not gonna like it, is that it's pretty easy to change your low fuel indicator light (and the other "dashboard" lights) to brighter LED's.
Personally, I like the grease pencil / sharpie method (even though I haven't yet used it!) - just write some numbers on the handlebar bracket. Add 150 miles, or whatever you decide is your refuel mileage limit, to your odometer reading and write it down. You won't even have to do any math on the fly; when your odo catches up to the number you wrote, it's time for fuel. I imagine a grease pencil wipes of readily; I'm guessing a sharpie would do the same (especially using a paper towel with perhaps just a drop of gas to help, although that may not even be necessary). Beats a trip odo, if you ask me!