I raised this same question re TBIII with my building gurus awhile back and was strongly advised not to go there. Advice was to lam up the riser and bake it in the kitchen oven at about 180, then,when baking the actual bow, hold the heat box temps to about 140 -150.
Incidentally, I like vintage bows, and walnut/maple lams were a common feature. I have a Root longbow with a 25" riser of maple and walnut that i am planning on building a duplicate of.