It's always possible to install your own flotation by using stuff like inner tubes, clorox bottles, foam-in-a-can, those 48" swimmer's foam tube thingies, empty Gatoraid bottles, whatever floats your boat.
Best way to do it is, install floatation as you think best, and then take the boat for a test sinking........easy....go back and adjust floatation as needed.....trial & error....never fails!!
Hmmmm.....am not sure if I'm kidding or not? If it's a small boat with no motor, it's doable. A motor in the water or a boat bigger than about 16'.....probably knot?
As part of my nine boat, FLL-NAVY, I have an embankment, roller-retrieval, winch set-up, capable of hauling a 16' boat weighing about 1000lbs up and out of the lake. Built from lumber, trailer parts & rollers, wood stain, and a hand crank winch, all retrieved from the Meredith transfer station. A side benefit of having a sticker for the Meredith transfer station!