The road from Interstate 15 to the campground is supposed to be maintained for highway vehicles, motorhomes & such. That being said my buddy managed to stick my dad's 22 foot motorhome in a sand spit that had drifted across the road. The EwePee maintenance road was another story; although I saw a M of W employee regularly drive through the Mohave River in his Cadillac !!! While 4WD may not be necessary, a vehicle with high ground clearance should be used. That being said, I've witnessed a Honda Prelude & 1980's Ford Mustang make it to the bridge @ the middle crossing of the river,during a railfan weekend back in the early 1990's. The Honda driver knew what he was doing, while the Ford driver was blessed !!!