Phil don't forget you fins under you boat
we usually add "Inboard Bunks" to lifts we install
this will keep the fins a safe distance from the cross rails
additionally we'll add either a bow stop or side rails or bumpers
so you do go in too far......... on my lift I have a piece of 1" pvc attached
vertically and lines up with my throttle lever, then I know the boat is in the right spot
water depth min max will also vary with the type of lift you are getting
a vertical lift has a much longer / larger lift height and some models can go all the way down to the
lake bottom, cantilever type lifts have a much much shorter lift height and require more min depth than a vertical
bottom line it's basic math to figure out a good starting point , then a little trial and error to get it just right
good luck
Dan T