"Anek/Superfast do Camping on Board, but not on one ship. However they do not specifiy which ship operates which schedule on which date. Also is it possible that one books for Camping on board and then they substitute the ship that does not permit it - then what?"
Its the usual confusion that you get with Greece ferries Geoff. I haven't checked properly but you used to be able to go online and it would give you a ship code for each crossing on their timetables. Can't find that at the moment but it might be there somewhere or be released later.
Anek/Superfast share the route,
Superfast have 4 ships on the route that I 'THINK' have the Camping on board' option, SFast 1, SFast II, SFast XI and SFast XII.
They are also advertising a 'camper special' (similar to Minoan with inside cabin etc) when the ship 'FB Asterion' is on a particular route.
Anek definitely have 2 ships that have the 'Camping on board' option, FB Hellenic Spirit and FB Olympic Champion. They also offer the 'camper special' when the ship FB Asterion is on their route so they must alternate that ship between both companies.
So, if we can find out which crossings FB Asterion are on we'll have cracked it.
Asterion is an Anek ship btw.
Clear as mud.
ps:- I accept no responsibility for any errors in this post