If I may add my two-penneth gents - I did a similar thing with the Cranberry Isle version,
I made the whole cabin and rear well with additional false sides into a one piece lift off unit !
A floppy structure that required stabilizing with epoxy and matting,
this was left to dry and cast itself into a solid unit while jigged into position in the hull, worked all ok in the end.
Sadly was sold to a foreign gentleman at Beale Park who made me silly offer for my pair of Lobster boats
and they went back with him to Singapore ? HoHum.
Andy guessing your forward cabin sides may spring out of shape a little (flattening the curved sides)
if you make the cuts taking the tension out of the timber,
temporary cross braces in the cabin and with the roof glued on, it should form a nice solid structure,
an interesting little conundrum.
H'mm wondering if I still have the plans stashed in the collection ! tempted to build another,
they sit so nicely on the water and create a nice wake when on the move for a smallish model. Paul