Given that you have seen the issue and have a solution to it, that looks amazing Dave! I can envisage that performing whilst under power on the lake
For your concertina doors, if you have counterweights on arms that pull the relevant sections of door inwards then that will force the set of doors to conform to the concertina as they rise. If the cable system pulls both ways then the counterweights can be pulled down with assistance from the brass sections weight.
I would make the arms slanted backwards to improve the action of the weights.
You will need weights that don't touch when the door is folded!