FYI arriving at 10% is no big deal at all actually. I've done it many times. The car keeps on top of you and you can even watch an expected vs actually chart of your charge. It will warn you if you need to slow down at all. Most of my roadtrips I'm driving 10 MPH over the speedlimit and keeping with the flow of the traffic.
Tesla tends to put more Superchargers in friendlier states and Texas is super unfriendly with sales and service. Keep the dealers associations happy and oil tycoons rich.
Tesla has made progress in Texas tho ... a fairly large state
... they need some more North-South Superchargers vs folks passing thru (West-East)