I think that's slightly different to what I was suggesting.
I'd recommend attaching a foam "nub" for the head directly to the fibreglass core using tape (or your canvas-and-glue approach should be fine too), and then building the padded haft afterwards and build the head over the nub and the haft. The end result should look exactly the same, it's just different underneath.
It sounds like you're suggesting constructing a padded haft the whole length of the core, then building the head over it (starting with your "triangular blob" nub which is held on with the strip of canvas). I've tried that in the past, and the problem was that the glue holding the foam haft to the fibreglass core came loose where it lay under the head, alllowing the haft to rotate on the core (and the head with it). That's why I'm suggesting attaching the nub directly to the fibreglass core using tape.
Of course, you may have gotten around this problem some other way. Perhaps your strip of canvas helps hold the haft foam to the core by applying pressure from the outside, although I don't see how that would work. Or maybe the way you glued the haft foam to the core was more durable.