I believe that a "name" opening act would have had it's pros and cons..
Main pro...it would have given Elvis some incentive to perhaps perform at a higher level in 74-77...
Main con...if Elvis didn't care..and had no incentive..
he would have been made to look worse than he was actually perceived..
I believe the Colonel thought
A. Elvis was big enough to hold in own,and draw a crowd by himself(correct)
B.No more expenses were needed...why pay for a legit opening act when every show was a sellout???