I nearly always dehydrate my own food to go hiking, no special equipment needed. I used to buy those Back Country packs of dehydrated food from Mountain Designs until I worked out how to make my own.
If you look at those commercial packs, you’re lucky if they’re over 20% meat and I’m not sure how that is calculated, I would imagine that the meat percentage in the dehydrated state is way higher than it would be when the contents are ‘wet’.
Homemade is so much better and you know what’s in it. I make something meat-heavy like a curry or a chili con carne. That way, even pre-dehydration the food is at least 50% meat / high in protein. I’ve used the oven method, the trick is to wedge a fork or something into the oven door so that it is pried open about 1 inch (25mm). This is necessary as all the moisture needs to escape. Typically, I will cook around 2 Kg wet weight in a big pan. This will reduce down to about 1/5th of its weight over about 12-14 hours in the oven at around 80 deg. C (175 F).
Typically, the commercial food is around $12 / 120g. Homemade is cheaper at around $20 / 2 Kg ‘wet’ so this equates to $20 / 400g dry. I looked at my daily electricity costs and surprisingly there was no real discernible difference in the couple of days when the oven was running.
Obviously, making your own is much more work but I prefer to know what I am eating. I will typically cook 120g of a dehydrated meal with 100g of rice to make an evening meal for two when camping.
The trick for me seems to be to spread out the food in the oven tray as thinly as possible. I also line the oven tray with baking paper. Especially as the food starts to really dehydrate, I scrape it around with a fork every few hours to ensure that it’s drying out evenly.