I have moved boat lifts over water with a 14’ aluminum boat, float bags and modular plastic dock. For short and moderate distances, the modular plastic dock works best. Twice a year we move four lifts with a length of my modular dock.
For the hydraulic cantilever lift, we strap the dock to the cradle and lower it so the whole lift floats.
Now I typically use the 14’ boat to tow rather than the ski boats.