Only need to do the last bandit challenge which is committing five successful train robberies but after I had to buy a new horse and got them semi-auto pistols I got no cash left so I'll have to save up some bounty pay-off cash first.
Side-note about them challenges, I don't think Rockstar understands that getting $50 from robbing townsfolk and travelers (challenge 7) is the biggest fukking pain in the ass. Unless robbing store clerks counts too and I was an idiot, most folks give you less than a buck, and that is if they don't try to buck on you with the shotty. The rich folks at St. Denis might give you 2 or 3 bucks but that doesn't live up to the amount of witnesses and police attention you'll draw. Either way I spent a shyt ton of hours just to get this challenge, then the next is stealing and selling seven wagons which you can do in an hour around Emerald Ranch and the next is leaving three people hogtied on the train tracks. It's almost like they make it easy for you after that shyt challenge.