I'm most excited by a different way to connect the drysuit to the boat, normally a skirt.
I don't mind spending money on kayaking, but even after emailing manufacturers and buying premium gear I always have to sponge out all my boats! Drytop/drysuit, creeker/playboat, this skirt/that skirt, always leaks with any combination. Skirts are the biggest weakness in kayaking apparel in my opinion. There's no reason we can't be tissue paper dry in there.
You've got a nice layer of expensive goretex over your waist smothered by layers of velco, neoprene, and more goretex making it bulky and damp due to sweat. It's a waste of money and poor design. Why I bother to wear a union suit when I get all stuffed together at the waist regardless, I'm not sure. Then the skirt itself is water absorbent, not ideal for weight or warmth. Most skirts let some water permeate the material as well, so a slight drip falls constantly.
If you had some other attachment method you could loose the velcro waist band and the excess goretex material from the overtunnel. Then you'd have a loose fit in the waist with just a draw cord. A standardized circumference flap of material could be on all sized drytops and drysuits with some type of standardized zipper or whatnot as previous discussed herein. Then skirt manufacturers and their retailers could carry substantially less inventory by carrying only one size "tunnel", thus reducing necessary margins and thereby overall cost. I venture this would reduce of the overall cost of manufacture of the outfit as well, via savings on both the skirt and the drytop/suit by reducing material, seams, and hems.
You should consider rethinking the skirt instead of the drysuit as most of the gains are in a redesign of this area. My experience with my Kokatat GMER has been hard to beat otherwise. Also, you may well be better off establishing yourself as a certifier or compatibility bearer than a manufacturer. Unless you have experience in making such garments you are likely ill prepared to compete. You strength may be in uniting manufacturers around a common standard and taking a tiny percentage (i.e. 0.005%) of sales.
I'd do it but I already run two businesses! Good luck and it's awesome you are making an entrepreneurial endeavor.