@Argo

Thanks

I don't know if this helps you but this is how I tackled the fin/fuselage joint. I used Network and blend.
Actually thinking about this more, I could probably get rid of the network and included that part in the loft of the fin shape.

I also tried Andrei's Loft-Loose-Exact for the whole fin including the fuselage fairing but it doesn't give tangency at the fuselage joint which results in undesirable shading highlights when converted to polygons and rendered. It really needs to be at least G1 blend to overcome the shading highlight errors.