removed middle seats.
1st - piece of 3/4" MDF covers the (split) rear seats when laid flat, butts up to tailgate.
2nd - piece of MDF with fold out 'leg support panels ' butts up to and just over the front edge of the rear seats to make lower half of bed.
3rd - Custom-made to measure memory foam 3" mattress (£85)
Gives a perfectly flat full - width bed, 5'8" long, leaves approx 18" gap at the foot for getting in/out, and dog...
Whole thing folds down to about 8" thick, stored 'vertically' against the backs of the front seats, held there by bungee ropes running from the now-empty runner channels 'up and over' to front headrests. V secure, not going to shift in transit.
Prob more comfortable than our bed at home

Derek