I am guessing you are referring to the Spirit 28 designed by Robert Finch and built by Glastron.
The bulkhead is only on the port side from what I can see and the compression post is a few inches to port of center. The cabin top is unsupported on the entire starboard side while there is a bulkhead to port. I suppose a beam could be added across the entire cabin top but there would not be any starboard support for it. The compression post could be doubled to starboard to better support the mast above it.
Do you have any pictures?
Living aboard in Victoria Harbour