4 by 4 without a doubt! With that heavy camper you will want it to be level when you park. To do that you will need to get up on blocks.
It is infinitely easier to climb up on a double or triple set of blocks when in low range and that only comes with 4 by 4. The first time it is raining and slippery out, and you want to get set up and level, you will appreciate it so much.
I have also used mine to climb up to the upper view sites that only campers can get to in some campsites, and often I put it into low range to back up under the camper to load as well.
Don't even think of going 4 by 2!
Mike
2012 Winnebago Impulse Silver 26QP
2005 16.6 Double Eagle
2018 Jeep Wrangler JK
previously Snowbird Campers,
Triple E Motorhome and Fifth Wheel