I would still seal the back if the wood is freshly cut. It's a pretty dense wood, and can crack, if the outside dries too quickly.
I would stay away from quick drying. Just rough it out into a bow layout with wide tips, and floor tiller. Clamp it to a form, with some reflex if you want, and it will dry pretty quickly. Force drying works well with mid weight Northern hemisphere wood, but is usually too quick for denser woods.
2" is way too wide from memory, most bows from guava I have seen were more like 1.5" or less.
Its diffuse porous so it doesn't have typical rings like oak, ash , osage etc. Wood under the bark is fine.