Not an epoxy, but I use Resintite (aka Cascamite) on wooden bows. It's relatively cheap, long shelf life, long pot life.
Fine white powder, mix with water... instructions say apply to one surface, but I apply to both for bows.
readily available in UK... Amazon do it in US I believe.
Regarding method, I wouldn't do any width taper until it's glued up. Your other reasoning seems good to me.
Del