How can I save a panel state on a JS41 ??

 

I don't think you can, you have to save the aircraft in the required config as a saved flight.

 

Beware that you cannot save and retrieve it in a cold and dark config, do a search here for "LUA cold and dark j41" and you'll find a C/D J41 "macro" that works great (FSUIPC is necessary).