Yeah, I'll miss the moon, but I should be able to do the ~20 miles before dark.
I would probably carry microspikes just in case.
Wouldn't Bright Angel Campground have water too?
I'd be packing as light as possible...probably 7-9 pound base. I'd bring a small mid, 20 degree bag, and down jacket for the North Rim in case of bad weather though.
As for mileage/elevation, I'm pretty sure I'm OK with it.
A regular long run to a local peak: 20 miles round trip, 4,400 foot gain/loss (8800 cumulative), in ~4:30 hours running.
This isn't too far off from a Rim to River to Rim.
I've done other trips with a similar profile:
Onion Valley to Whitney Portal, including Whitney summit in <36 hours, etc.
I'm certainly not trying to overestimate though.
Thanks for all the tips folks. Not sure if this will work on such short notice, but I appreciate it.