The OP might also wish to call AA and inquire about award availability on China Southern, via Wuhan or Guangzhou. AAdvantage awards on China Southern cannot be booked at aa.com.
It's been reported that trans-Pacific Business Class awards on China Southern are hard to find, but there's no harm in asking. If nothing from Bangkok (either airport) is available to CLT, I would inquire just about awards to China Southern's North American gateways (JFK, LAX, SFO, and YYZ), and then consider booking a separate award -- on the same PNR -- from a gateway to CLT.