In reply to tallsteve:
I have seen someone put up a small tent in the foyer area of the Northlink Aberdeen - Orkney/Shetland ferry.
And agree, the reclining chairs are horribly uncomfortable. Northlink have converted some to "sleeping pods." They are rubbish, chairs which don't recline properly, they tip back but you are still bent in the middle, a hood so you don't look straight at your sleeping neighbour (that bit is good), and a blanket which is so small, it wouldn't even cover me - I'm 5ft tall. At least there is the expectation that people shelling out a little extra for a pod will be quiet and actually sleep rather than yakking all night (or worse).