Hey Scott D , I probably wont change your mind , but I would take a rift sawn board any day . you can send them to me if you want.
. you have to look at the whole picture here. If you take a look at that grain from the end that you cut, you should see that the annual rings still run from front to back for the most part. Couple that with the fact that you will be narrowing the tips to 1/2" or 3/8"(?) gives you good solid wood . I like it because you have multiple growth rings ,sort of laminated up, so you arent relying on one (possibly suspect when you haven't harvested it yourself and gone through the drying process) ring for the back 1/8 inch that's doing all of the tension work. You're right though, board bows have their own peculiarities and a backing never hurts.
If you do decide for a hickory back ,Kevin, I would suggest keeping it about 1/8" thick. Plenty enough to do the work ,without overpowering the belly. Trapping is another option but will give a totally different look to the bow.Good luck! Can't wait to see the pics.