Jeff...
I just did a mapquest search for the address of the stadium and then did a search for the nearest RV Parks to the stadium.
I came up with two parks
Pecan Grove RV Park
1518 Barton Springs Road
Austin, Tx 78704
512-472-1067
Mid Town RV Park
720 Airport Blvd
Austin 78702
512-385-2885
I have not personally stayed at either of these parks, but they are relatively close to the stadium. You could certainly check to see if they have a website and if it would be suitable for your stay here. I make no promises!!!
Lone Star RV Park is the nicest one centrally located right off I-35 and just a few miles from the stadium - we have stayed there before and it is very nice.
www.austinlonestar.com to view their website
Have a safe trip down and good time while you're in our great state!
Sandy