First.. Get the Howard500. Although trying to stop flying it (best sim plane yet) long enough to try THIS challenge, is challenge enough    

Start on Catalina Is. (KAVX) and try to make it to Hawaii (PHOG).

Realisms settings high.. Auto-mixture OFF.. and use the auto-pilot ONLY to hold heading and altitude (so you can speed the sim up at times) (NOT to track a GPS course(ie. leave the A/P NAV button alone)).

Without any significant winds aloft (headwind would make it impossible, tailwind easy) Try to manage your: MP, mixture, prop-rpm   during a carefully calculated climb and cruise (you won't need to be worrying about a descent on your first try     ) and you just might make it..

*don't spend too much time idling on Catalina
Good luck..