longer wheelbase and a diesel would take care of the needs you mentioned. Cut the TJ tub and stretch to LJ length. Swap out 2.5l for 2.8lCRD out of liberty or source one from foreign JK, cumins 4bt could also fit the billet, though it is an unrefined engine and has poor road manners, a toyota or worked Mercedes Benz diesel would do well and as HPA Motorsports has shown, the 1.9 TDi with nearly 3o0ft lbs torque could also do the trick.