The only place on my recent ride from California to Houston that I saw those camera cars were in Prescott Valley, AZ. I have never seen one anywhere else I've been which includes Texas. There is a rhyme that I've heard some people use reportedly from some law enforcement folks:
"eight safe, nine mine"
On interstates I generally run 10mph faster but you do have to watch some of the small towns. I got a ticket in a small town approx. 80 miles southwest of Abilene last year where they had a sign dropping the speed limit 20mph after a bridge under the trees just before a downhill grade with another 20mph drop at the bottom of the hill.
As for the rider if you are staying on 90 all the way through Texas there's a rally in Houston this weekend. http://hiptobesquarerally.com
where I know some Helix fans will be attending.