The 4WD option will bring almost as much on resale as it cost new. Now days, the only additional fuel cost is for the mere 200-300 lbs weight difference. If you only need it and use it one time, slide off the road, or worst case, really get into some doo doo, it just paid for itself. I drove 2WD diesels back in the early 80's. Got tired of getting stuck on slick spots. The weight of a diesel engine is a detriment in a 2WD, a compliment in a 4WD.
Scotty and Kristen, Airedales Dagny and Wyatt
2007 Newmar Mountain Aire 4528, 450 HP ISM, Allison 4000, 8 Trojan T-105's
2014 F150 4x4 Crew Cab Platinum 157" WB
Roadmaster Blackhawk 2, RVI2 Brake System