Have you looked up what is available from the fish suppliers in your area?

Hybrid crappie typically have increased growth and lower reproduction in the first generation. I don't know if you can overcome the typical problems with crappie in small ponds, but you might as well make your job easier!

Hopefully, some of the actual crappie experts will chime in.

P.S. 8 feet might be a little shallow if you get a brutal West Texas summer.