Purely speculative on my part, but based on the buildout of I-80 in Nebraska, I think Tesla is trying to keep the segment legs on these routes a little lower, more like 100 miles. I-10 is a little tough to do it well, so some of the legs may need to be a bit short.So, that said, maybe something like
Casa Grande - Tucson ~ 70 miles
Tucson - Willcox ~ 80 miles
Willcox - Lordsburg ~ 75 miles
Lordsburg - Deming ~ 60 miles
Deming - Las Cruces ~ 60 miles (perhaps you can skip Deming)
Las Cruces - Sparks ~ 65 miles
Sparks - Van Horn ~ 105 miles
Van Horn - Ft. Stockton ~ 120 miles
Van Horn - Ozona ~ 107 miles.
That would end up being 8, 7 if you take out Deming. Although I like Deming as it's used as a shortcut to get to I-25