I've got a 2013 Ram 2500 4x4 5.7L Hemi Tradesman with 3.73 and 17inch rims. The truck has 2,500 lbs of payload and 11,500 tow rating. I'm not sure what your pin weight will be with that fifth wheel, but it should pull it fine and be a stable platform. I would double check your payload numbers. I pull a 7,000 lb TT and haven't had any problems passing in the mountains or anywhere. The 5.7L Hemi is very powerful at 385 HP (2500/3500 HD) 400 lb/ft of torque at 4,000 rpm. The only other gas engine that compares to it, is the Ford 6.2 same HP and 5 lbs more torque, but at higher rpm. I believe Ford did increase their torque this year, 430 lbs at 3,800 rpm.