Paulownia is grown and harvested in the eastern US, and when resurching it i found that most of the lumber is made into siding. The siding is fingerjointed and there are knots in most of the boards so there is a bit of wast and using a plane is a somewhat trying at times.
The wood is lighter than WRC so with the plan to paint my hull I used the Paulownia siding cut into strips to make the hull. The deck will be finished bright so I used WRC for the deck. The entire 19'8"x20"hull / deck combo with 3OZ glass and 3 bulkheads came in at 17 LBs, it still needs hatches, rudder, seat ... but I think the total weight will come in at about 25LBs when complete. If you stay away from the knots the wood seems to work quite well and the price even with the waste of working around the big knots was less than WRC for me. This is the product I used, you may be able to find it in your area, or if you are on the east coats there may be common lumber avalable without all of the fingerjoints. http://www.snavelyforestproducts.com/products/exterior-cladding/trim/kimberly-bay-primed-paulownia
Have fun, enjoy your build,
Walt