Would you get it in the lazarette? I doubt it.
We have a 2.6m Highfield RIB and we store it upside down on the aft cabin roof under the mizzen boom, bow facing aft. It JUST fits.
We had a custom elasticised Sunbrella cover made for it and it's held down with webbing straps to the rails on the cabin roof.
We have sailed across the South Pacific with it like this and have not had any issues even with white water coming over the boat.