You might give Ben Diller at Savage River a call to discuss various strength and durability options of their layups. Last fall I received a new Blackwater solo canoe in Texreme Lite, promised at and measured at 19 pounds. it is to become my new flatwater and slow river tripping canoe. I have no intention of using it in fast water or being rough with it in any way. I am enjoying my first paddling this spring in it and I love it. Way more stable than a PB Shadow and just as fast, or faster, especially in wind. I also enjoyed working with Bill Swift a couple of years ago for a new carbon fusion Cruiser. with even greater stability for my daughter.
Can I ask more about your Blackwater?
Their layup pricing/weight spreadsheet shows the Textreme Ultralite as 19 lbs...Textreme Lite at 21.
Did you actually get the Ultralite, or did you get the Textreme Lite & make other selections (like the interior layer) to bring the weight down?
Carbon fiber thwarts & handles, or Aluminum? Stock seat? Foot brace? What else?
My Blackwater is great, but I do dream of getting a lighter one. 19 pounds is pretty sweet for such a rocket.