I think just DX11 along with disabling advanced physx did the trick for me, i have no idea what causes it and it seems even consoles has this issue, tons of people have it or they dont.

I fixed one crashing issue by limiting the fps to 60 in the Nvidia Control Panel, but that was for the Two Colonels DLC. In my experience, the beefier your system, the less crashing you experience in this game. Caspian is one of the harder areas to run in the game. Glad you got it sorted though!