I think you hit the nail on the head Craig. I posted earlier about how you can see he saddle bags, different windshields etc in the teaser photos.
Putting my auto manufacturing hat on, I can see Morgan offering just as many interior trim options on the new M3W as they currently have for the Plus Four/Six as that is an easy win due to production being in place. i.e. contrast stitching, perhaps introducing piping, different seat patterns etc.
Those saddle bags point to an accessory rail/attachment system which then opens up a pandoras box in what Morgan can offer. My vote is that the majority of what can be customised will come from bolt on parts which can be done efficiently and even after taking delivery.
I've been toying with the idea of putting a deposit but I'm holding tight until I can touch and feel one.