Generally, a wood that we would consider "extremely light" (can you test a piece to calculate the specific gravity?) is not a great bowwood. It will be especially bad in a deep bellied bow, such as a true English Longbow, even at only 45# of drawweight. A lightweight wood should be used in a low stress, low strain design. That means a long and wide flatbow, with a flat belly. If you use the same wood in a longbow that is 4" longer and has a belly that is less crowned, you may just succeed.
Your idea for a warbow sounds good as well. Please keep us updated!