On 6/16/2022 our vehicle did not allow me to pull my boat and trailer up a gravel road hill leaving our RV Park at 31733 Aqua Vita Road, Gravois Mills, MO 65037. a)Front wheels started slipping but the rear wheels never engaged. b)Either the brakes were applied or engine power was derated despite application of the throttle. c)I didn't just continue to slip the front wheels but kept stopping, adjusting the traction selector and then try again until a warning pulled up "AWD Overheat, Stop Vehicle". At least twice during throttle application there was unanticipated rollback of the vehicle. a)This sudden rollback surprised me and by the time I could react, the vehicle rolled back several feet, sliding in the gravel back down the hill. b)This rollback was partially uncontrolled and caused the trailer to back at an angle down the hill. c)The trailer backed into a tree just off the road keeping the trailer, boat, vehicle and 5 occupants from rolling off the side of the road d)If not for the tree there would have been great personal property damage, physical harm to the occupants, possibly even death.