You may have already done this but here goes....
I got out on the MSF website and went through these steps to get a list of 3-Wheel Basic Ridercourse listings within 500 miles of Amarillo. First one listed is at Pampa. Even found one listed right here in Kerrville!
Motorcycle Safety Foundation website
Choose: MSF Core
First column on left, choose: Basic 3 Wheel
Input Amarillo zip code: 79101
Change search radius..scroll down to 500 miles: 500
List shows up.... Pampa TX is first one on list
Hope this helps!