Some tinker time with the trailer today. The bunks were sitting 3" higher than needed, the transom wheels couldn't be fitted unless I wriggled the HW back enough, the bunks at the stern extended a bit far causing problems loading/unloading.
I decided to drop the bunks 3", which in turn ment the SIB didn't need to be so far forward for the bow to rest on the winch stopper.
This allowing the transom wheels to be fitted/removed or left on without the need to wriggle. I even had the option to mount the wobble wheels on the back of the rear crossmember, supporting the transom.
Happy with the result as I can easily dry launch and wheel to the waters edge on my own.