If all you need for now is a spot big enough to park a camper then I'd cut them down leaving a foot or two of trunk remaining and then pull the remainder. Their small stumps and there's lots of ways to get rid of them and your truck may be one of them. A chain and a farm jack or even a engine hoist work great too.
Honestly even if you had full lockers you would still have exactly jack #### for traction. No weight. Even less weight if you hook to the tree at higher point than where you attach the cable to the truck. All in all I see this as a very bad idea with the potential to cost much more than buying 2 or 3 decent chainsaws.
Winner. With weight on the drives you got #### for traction. Put enough weight on them to get traction then when you run out of chain your gonna be flirting with breaking an axle.
My question is how are you going to log that ? Just hire somebody with a skidloader and tree shear .. gezzus