I believe it is the IB250/2. As standard, it looks like this:
The first two photos below show the boat on it when I first got the trailer. The 3rd photo is not very clear but it now has longer bunks on the sides (the uprights indicate the ends of the bunks) and a strip down the middle made of the same material as the bunks. The side bunks are blocked up slightly to ensure the load is shared between all three bunks evenly.
The fourth picture shows the outboard support. I have now lowered it and turned it through 90° to give better support. You can also see the end of the left hand bunk. The centre bunk extends about 10mm beyond the transom. There is also a trailer roller immediately behind the centre bunk to assist with rolling the boat off its trailer onto its transom wheels for launch.
I'll try and take some better photos of the current setup at the weekend for you.