And ya, 55m makes for a pretty short dive if you are trying to avoid much deco...
There was an accident in Sipadan in Mar this year where the body was found at 55M. When I was diving there last week, I spoke to the DM who pull the body out. He said that the tank was empty.
I've checked the air requirements for the dive based on a RMV of 18. Diving with either two tanks of air, or one of air and one of EAN32 will not allow too much time at 55M.
Since the wheelhouse is at 37M and the main deck is at 45M, there is certainly no need to reach the bottom of the wreck at 55M. We may opt for a longer and shallower dive.