piper, I cut the potatoes into about 3/16, 1/4" thick slices once they have cooled down, then cut those into little squares. Maybe 1/2" on a side max, then put them on the drying trays. I cut out some screen and put it into the drying tray to keep the little pieces from falling down.
My first attempt I didn't cube them after slicing, and had to use a hammer pounding on a towel wrapped around the potatoes to crack them, a big mortar/pestle barely dented them. Took so long to break up the big pieces I decided that the extra cubing time was time well spent.
These will rehydrate quite nicely with a cozy, takes about 15 minutes, 20 to be safe. They don't get soft like a potato again, but they get chewable, and taste really good, and also don't fall apart into mush. I'd guess that if you are going to be high, 8k or more, you might want to slice it thinner to start since the water won't get as hot.
This stuff gets so dry you can probably make a year's worth at a time safely I'd guess, like the dried boiled brown rice.
Slicing the potatoes is a bit time consuming, but just put on the radio or something and be zen about it, when you're done you're done and can do other stuff.
This stuff is so relatively easy to make that I can see no reason to ever buy it, the only real time is the drying part, plus you can source the potatoes/rice and end up with far better quality than you'd buy.