Diesel?
We tried pulling our Elk Ridge with a 1995 F250 V8 (gas), and while it was within ratings and could pull it... we didn't feel safe. The 2011 probably has better brakes than our '95, though. We were told that the gas engine would do fine, as long as we were OK listening to the engine run at high RPMs, doing 25 mph over the mt. passes.
We now have a 2008 F350 Diesel, which does a great job and is much more comfortable to drive. Very happy with our upgrade!
-T