Hi,
I bought some bed slats from IKEA. They fit nicely between the two bunks
in the main cabin (I added stops for them under the cushions that double as
a holder for the "dry mesh" ventilation I put under the cushions). You just
slide over one of the cushions on top to make a double bed with a space on
one side (or move both cushions and have a space on both sides). They roll
up and will fit under one of the bunks. They're birch plywood - probably
not marine ply but in three years I've not seen any sign of delamination -
they're only used inside anyway. This is a very cheap option that is
probably more comfortable, easier to stow and at least as strong as a solid
ply solution and I'd recommend it.
UK link:
LURÖY slatted bed base, 90x200 cm. Curved slats adjust & open design promotes airflow. Keeps mattress fresh.
www.ikea.com
Regards,
Tom