Hi Pete, my girlfriend and I have just met the race in Tucuman. We don't really know more than you at this stage but would be happy to share anything we do learn with you and coordinate our efforts. Suzie can speak reasonable. Spanish which is handy.
Some locals in a couple of places have told us competitors will start tomorrow on route 38 and support follow route 9. That doesn't match the map now released on the Dakar website - looks more like route 157. Riding through Frias yesterday, we found a pamphlet in a petrol station advertising the town as a spectator spot. Based on the official sketchy map it looks like they miiiight start the special around San Pedro. We were also told by a local in Recreo that it was going through there. They are on 157. I think we'll follow them out in the morning if we can and see where they go.
All the best, might run into you somewhere. Sorry for any typos, my phone is playing silly buggers.