Some more progress photos and comments
A little "balsa bashing" was necessary to obtain a better fit to the wings.(A closer photo of the gap from the last set of photos)

With this achieved the upper fuselage was epoxied to the wing and the carbon rod was held in place with the masking tape and then cyno was run along the joint. (I've found that this is more than adequate to join carbon fibre to balsa).

The lower sections were then epoxied and cyno'd. And left to cure.