Sgian Dubh
There's certainly good reason to do what you suggested, i.e., cut pieces close to length prior to deep ripping, then stack with stickers and clamps. All the same, I still prefer to partially flatten as I described earlier prior to resawing. As to working wood with an unknown moisture content, that's easily determined if really necessary with either a moisture meter or an oven drying test using a microwave oven, some reasonably accurate scales and a few paper towels: a half to three quarters of an hour task using a microwave.

Either method for testing MC would determine if the material is too wet for deep ripping (or any other task for that matter), and I'm not sure why anyone would choose to use material that's too wet for the job in hand. Too wet for me in this situation with this sort of task planned would be material that's above about 12 - 13% MC. I find I can get a reasonable idea of wood's MC just by working it with either hand tools or machines. Dry stuff works differently to wet stuff, in that dry stuff has, for example, a 'crisper' sound than wetter stuff as it's cut with a saw or planed, and there's the quality and form of the chips and shavings that provide the worker a clue to moisture content. Slainte.