Dual cat on cal. truck

Alright guys im new to the TW so keep me straight if i veer off into the wrong path. I have a cal emissions truck and not if that effects me or not since im registered in NC. My cel has been on for some time and i know my cats are bad but the dealership wants like $2800 bucks just for the oem cats. Would like to run a single cat or 2 if i have to with a o2 simulator. Any suggestions of inputs will be appreciated.

 

My truck is registered in NC. No Military

 

i have read other forums where these issues have been converted to single cat with an o2 simulator. can find aftermarket on ebay buy not sure which one is correct if im gonna change it from factory conditions. just curious it know if anyone on TW has had personal experience with this issue