What is the shelf life of dehydrated, precooked meals?

Dehydrating food is a common practice for trekking and backpacking. Dehydrating vastly reduces the water activity in foods, making them a less hospitable environment for bacterial activity. You'll want to use a reliable dehydrator with a variable temperature setting, as different ingredients require different temperatures and times to properly dehydrate. I think it would be better to dehydrate your ingredients individually, then combine them into meals. For example, Backpacker Magazine has a handy guide with some good suggestions. Dehydrated vegetables have a very long shelf life. From my internet research, it seems that many folks recommend consuming dehydrated meat within two weeks. I'm not sure you want to freeze your products. They might become moist when thawing, thus beginning the re-hydration process before you want. This could theoretically impact safety.

I am afraid food safety does not work the way you imagine it, or the way that would be easy to deal with. I cannot write up a whole course on food safety here, but here are two facts pertinent to your question.

1. Shelf stability is a truly binary outcome. Your food either supports bacterial life - which means it is only good for a total of 2 unrefrigerated hours after preparation - or it does not, which means it is good indefinitely and any "expiry" dates are a matter of degrading taste. There is no "slow bacterial growth" state in which the food is safe for several days or weeks or months, but stops being safe afterwards.

There is a bit of an extra twist with all methods that use reduction of water activity to make a food shelf stable (these include dehydration, or jam cooking): since molds need less wetness than bacteria, your food can become unsafe through mold. This is usually not included in safety calculations, you just consider your shelf-stable food safe until you visually see the mold, at which point it is unsafe.

2. You cannot predict whether a given recipe will produce a shelf stable food. The only way to know is through testing.

It doesn't matter how many parameters you use for the prediction, the process is too complicated to be described mathematically. So any recipe which purports to produce shelf stable food has either been tested "naturally" (by having been used under unchanged conditions for centuries) or in a lab. Note that you cannot make tests for safety yourself - just because something did not make you sick once, or twice, or 100 times, it doesn't meet the criteria for safety.

So, you cannot just pick any food you like, dehydrate it at some temperature, and declare it safe. Nor can you calculate a combination of dehydration time and temperature which is certain to make it safe. You have to find recipes which are either very specific (e.g. someone created a recipe for dehydrated stew that was tested to be safe, and it will have to cover everything including the exact ingredients, stew cooking method, and dehydration method) or apply to a class of foods with known wide safety margin for dehydration (it is pretty easy to make fruit safe by dehydration).

To answer your question directly:

I want an estimated for how long they are safe

The literal answer here is: 2 hours. For any longer duration, you have to use a known recipe that has been designed and tested for safety, and it is impossible to make up that recipe by yourself.