I was thinking about the floor boards and the removable sections. There many options and possibilities to consider. The plan is to have lift-out sections between bulkhead 8 and floor 6 for access to the drain plug in bulkhead 8 and some (limited) storage. From there will be lift-out sections (for ballast) to floor 4 , and then another lift-out section (for storage and battery) from there to bulkhead 2. The boards of these sections will butt against each other on the center of the floors, in line with the screws of the other boards. This arrangement should look OK.
The section between floors 3 and 4 has glass on both sides, and there are some more cleats in various locations.