Best way to preserve nutrients while dehydrating fruit and veggies
Dehydration in all ways spoils nutrients. There are few tricks (like freeze/dry dehydration, sulfur dehydration, and orange juice bathing), but in the end you will always loose something along the way. That said, home dehydration is not as bad or aggressive like industrial one is, so you will probably still end up with a positive weight/nutrients ratio. But, be aware that being sugar much more resistant than everything else and much more present in fruits and vegetables, you'll basically end up with "lot" of sugar and few nutrients. From this point of view, fresh fruit is always the better trade off.



That said, maybe you can solve your problem if you look at it from a different perspective.

So, first a step back: as of today marketing is trying to convince people that the more, the better; things like "if 100% of the daily recommended intake make you healty, imagine how super you will be with 1000%". Now, that's entirely marketing bull***t, dangerous for your health and on top it even if for some vitamins or minerals it could be not dangerous to exceed, it will force your organism to do lot of work to expell all that is unneeded/unused (yes, there is practically no "storage" of nutrients in our body)

Then, if you want to bring your own dehydrated food with you, instead of worring about maximising how much nutrients will remain after dehydration, maybe just do the math to understand how much dehydrated food you'll need to bring with you; maybe you'll discover that even after loosing 90% of nutrients you will need just a couple of hectograms of dryed food instead of 2 kilos.

That said...try not to kill yourself with spoiled dryed food or by doing the wrong math and bringing a 2 days reserve for a 5 days hike, ok?