I've been thinking a lot about this option. Since the width at the nut is currently correct, the maple "binding" would taper off toward the nut. I honestly think this would be a cool look, but it's definitely not the kind of aesthetic I originally had in mind for this build.
There are two alternatives for laminating.
a) First glue up maple and rosewood in the correct thicknesses, make wedges from that assembly, and then glue those to the neck. This would give the most natural look, but if not done accurately there would be some odd looking spots. For example, you'd likely see where the rosewood isn't the exact thickness of the original board on the heel of the neck.
b) Slim the neck down further at the nut end. I could then add the "binding" in a consistent thickness all the way down the neck.
Both of these would be pretty challenging, but I might be able to pull them off. Ultimately, though, I'd still have a neck made with some compromises.
Overall I think I'm leaning towards installing the neck and bridge as is now, and then building a new neck for the guitar a few months from now when it's easier to run out and get supplies. It would be easy enough to re-route the neck pocket to accept a wider neck, and I can use this neck as my practice run. This will also give me a chance to see what I like and dislike about my neck (in terms of shape and thickness) and make other adjustments.