I build mostly board bows, mostly osage these days but I've been through a LOT of woods. Absolutely, if you want this bow to last and be as good as it can be, stop right now, flatten the back and glue on some bamboo. I made a lot of bows with pignut hickory (the best hick for this purpose) but got tired of them cracking; it just doesn't happen with boo. However, boo will take much more a "set" than hick, and with a long and straight longbow, hick will likely suffice. It's easy -- just get a thin lam of backing and glue it on with C clamps, then re-tiller the belly until you have the weight you want plus 5 or 10 pounds ... as it will gradually get weaker. This is by far the easiest, cheapest, and highest-odds way for beginners (which I still am, some 40 bows later!) to build a bow: board with backing. Have fun.