I need to build some kind of lift or cart to get my parents down to there dock on the lake.They are not confinded to wheelchairs.The weight to pull will be min.200lb,max.800lb.The pull will be about 200ft,the drop is about 15,20ft.Stair lift chair i don't feel will work due to the drop down stair.I thought of winches with a cart,just not sure how to hook up.Mom' says as long as it stops at the bottom not in the lake.Any information might help them cach a fish.Thank you.