We have a lot of variables to consider calling him dead or alive. did they look in the right place, lots of the search area was thick brush. did he take the case or toss it. if he tossed it he might of emptied the contents prior to tossing the case. it's literally, extra luggage. if he survived, he kept his mouth shut which is uncommon with most crimes. they end up telling people at some point.
Certain pictures of Rackstraw do make him appear older than his real age. McCoy is another example of not looking his age. still doesn't make them Cooper. both have been ruled out for multiple reasons, prints, DNA witnesses etc. even Duane Weber in his younger years looks like Cooper. he couldn't even steal a woman's purse without getting caught. the guy spent half his life in prison over stupid mistakes.
I would like to believe he made it and beat them. I just don't know...