I don't know enough about this to give you a good answer, and since no one else has chimed in, I think your best bet may be to try to contact some commercial packaging operation and see if they have suggestions. Your quantities probably won't be big enough to interest them, but maybe they can point you in the right direction.
I think packaging is going to be your biggest hurdle. A complete air seal does amazing things for cookie shelf life -- a traditional tin often seems to double or triple the shelf-life of my cookies compared to other less sturdy or air-tight containers. Even things like the plastic trays that packaged cookies come in are no accident: they often keep the cookies well-spaced (no mass of them sticking together) and won't absorb or give off moisture.
As for the recipe, I don't think you'll need to go as drastic as dried eggs, etc. if you have proper packaging. The recipe may require some tweaks or preservatives, particularly for soft-baked cookies. The earliest packaged cookies were generally dry and hard -- think "animal crackers." At home, I can make cookies like that which last for a couple months stored in a tin. But I think "soft-baked" cookies only became common in commercial packages in the 1980s or so. (However, the texture of those "chewy" cookies was generally horrid.) I imagine one reason for that may have been the increased use of hydrogenated oils at that time, which would have allowed higher fat content without the fats going rancid at room temperature during storage. Rancidity is probably your next problem to solve after achieving a good air-tight seal and packaging. (Lecithin in very small quantities might be a little helpful too, but it can impart a strong flavor.)
You might need to tweak the recipe a bit if it's too moist, and that should help to avoid microbial problems or mold. (Yes, cookies -- particularly moist ones like soft-baked -- can grow mold, but we generally never see it because the oxidation causes staleness and rancidity long before we generally see mold growth.) Aside from lowering moisture, increasing sugar and/or salt content might also help.
Those should be the main concerns. Other preservatives may add a bit longer, but the biggest hurdles are packaging (including a real air-tight seal), rancidity, and mold. Conquer those, and you may already looking at a shelf-life of at least a month, maybe a few months. Beyond that, and you'll probably need to start experimenting with recipe tweaks like the big cookie companies do. Unfortunately there aren't that many "magic" preservatives that will push staleness off forever: a lot of it just has to do with getting the recipe with the right fat content, moisture content, etc. and packaging them well.