I have looked at it, but got nowhere because PTY is a destination that can only be reached from either DFW or MIA, which plays rather badly with the rest of your stops and the number of segments available. Is PTY or bust or are you open to suggestions about other places in Central America?.

If you let us know your must see places in USA/Canada, and the max number of segments allowed for the whole of NA it I'd be happy to delve further into it.