The ride from Creel into the canyon is some sweet twisties... and then the gravel into and through the canyon to Batopilas is lots of fun.
spares kit doesn't need to be significant, remember; light is fast... and easier to lift up when you rotate into the ground
tubes: front/rear (only front if you want to run super light), put it in a freezer vacuum bag with a little baby powder, then stuff it into the upper fairing.
clutch slave: replace with Oberon and refill with 5w synthetic suspension fluid
water pump: upgrade to 07-08 990 shaft and seal or CJ's super shaft and seal
tires: for the given terrain, i'd run Heidenau K60 rear and the aggressive pattern K60 front. Will easily last for 5-7k miles.
support/safety: spot tracker, may or may not be interesting, not sure if they cover mexico or not ???
navigation: Check out dualsportmaps.com and the Droid GPS app. I run it on a 7" tablet, hands down better than any current GPS on the market for DS road and trail detail in a format that is usable when navigating unknown trails/roads.
I went through my bike with a fine tooth comb, re-loctited fasteners, changed all fluids, updated the fuel pump to a Facet and changed out the WP shaft. I was running TKC80s, which worked fine but were mostly done by the end of the trip.
Only regret was we did not spend more time in and around Batopilas, one day in, spent the night, then rode out the next day out to Creel again.
Enjoy the ride, its amazing.