Never an easy answer, but here goes.............
If you stack unfinished boards outside, it really needs to be horizontal; vertical stacking is not a good idea.
Keep it layered with 1 inch square sticks at about 2 foot intervals along the planks. The important part is to keep it out of direct sunlight, (in shade), keep it well covered with a good overhang all round so that it doesn't get rained on or blown onto. Doing this will ensure that the moisture content will eventually acclimatise to your natural surroundings.
When you get around to using it, cut the stuff oversize and (sorry about this) defy the missus and keep it indoors (in stick) for a few weeks to acclimatise again.
Anywhere will do -behind a sofa, under beds - but away from radiators and direct sunlight. This will prevent any new movement in the boards after another change in environment being a nasty surprise at the gluing stage. As they are oversized, you have some latitude to deal with new movement, twist etc.
Alternatively, if all this is impossible, you'll need a considerable extra expense buying in ready-prepared stuff....... but even then, if you did that, I'd still stack it indoors for a few weeks before use.
Good luck.....
