Has anyone tried fitting a 'donut' inside the dome port? This will totally block any stray light from hitting the inside of the dome. Certainly any reflective surface on the front of the lens need the matt black treatment as does any reflective surface within the dome port.
Here is a question for the people having this problem. Are any of you using the internal camera flash? if not where would the light come from if it is reflected from? The donut is a solution for internal flash problems.
In the case of the Simppu picture http://johan.kuvat.f...7.JPG?img=small the inter ring is the hole where the port body attaches and the outer ring is where the acrylic dome attaches to the dome backing plate. The only way to really attach the flocking paper to the dome backing plate is to disassemble the dome. This is easily done by removing the outer o-ring. However I do not recommend that anyone try this as re-assembly is quite difficult without a vacuum device.
I find it inconceivable that Aquatica cannot help you.
Since Aquatica made the housing, they should have the dimensions of the camera tray with its specifications on file.
I have ask Aquatica for the part and they report back no stock. I ask them for dimensions / drawing of the part and they have not as of yet replied. I am sure there is a approval process for this so I am waiting and continuing to look for other solutions.