I had the same challenge when on the hard
at PSS Satun in December. The boat was supported on its two keel
bases and what we did was raise one end of the keel
at a time, with a supported hydraulic jack, just enough to get a small paint
roller in and then lowered it on a hard wood board. Effectively twisting the boat every so slightly - but it does this in seas so no worry there. However I still didn't get 100% coverage but near enough.
Its a bit worrisome though. You have 16Te resting on two keels of approx 1m square each. Thats a lot of weight on a small area. I think the balance of the boat is good, its been designed for it, but suggest you keep your water
and fuel tanks
low and the clean and paint it as quick as possible.
Note that Lagoon
recommends that the a 100% keel base is to be supported at all times - obviously.