Alright I think I'm starting to get the picture here, we need people who can do things more than get things. So maybe instead of an excon on the run, It would be um, somebody familer with robotics and mechanical stuff instead? Like your guy is an engineer but you can always use more right? Cause the entire ship is over 60 years old and everything needs a tuneup. 

Also, we could probably do with having a doctor on bord. Or at least somebody with a medical history. They would also probably be the best to man the 'artificail wombs' and smuggle the gametes. 

Beyond that though I'm kinda drawing a blank as to who you'd want on this journey to mars.