"If you pull a travel trailer rather than a 5th wheel, you'll be very surprised how easy it is in 2WD to be unable to get moving uphill from a stop on even a slightly slippery surface."
Hadn't thought about that much, but I do remember some interesting times trying to get my boat out on the concrete ramp in Tillamook, OR, when the ramp was covered in green slime. I had a RWD car at the time so 4WD wasn't an option. With every attempt, the wheels spun and the car and trailer slid a bit further down the ramp into the salt water, with the boat floating off the trailer. Fun.