New Best Way to Level Up in Red Dead Redemption?

I've been playing Red Dead for a while. I've entered into Legend once and am now level 15 on 1st Legendary. I've been grinding Twin Rocks for all my XP for most of the 65 times I've leveled up and it's getting a bit old. I was wondering if there is an easier way? I have the Liars and Cheats DLC (the one with the Explosive Rifle and all the new gang hideouts/hunting grounds) so I have a few more options. Any advice is appreciated. I am on the Xbox 360 so I don't have Solomon's Folly sadly.