Moisture

I swear I saw 500mm when I checked that website..

I saw your comment re. Rigid fork before you apparently edited. When it comes to tackling more challenging terrain, a suspension fork for sure can offer some greatly improved rolling stability. Rider skill is another big factor here. A light bike is easy to finesse over roots, rocks, obstacles etc and help carry momentum by picking a good line.

I prefer to ride something a bit less technical and more flowing, where a rigid fork can really shine with its more dialed in behavior as well as fast transient responses. But I will be riding everything I can find in my area in the meantime, meaning I'll need the suspension.

Also, if you do use a rigid fork, a 27.5 wheelset with some really thick 3.0" tires can really help to make up for the lack of suspension. Perhaps you can even use just a front 27.5" wheels with a tire that matches in diameter front to rear for that extra cushioning.

If you look at something like the salsa fargo rival, this would definetly fit the bill with its thick 27.5 x 3.0 tires, and a MTB style Firestarter fork with a 483mm atc.