I jumped into gravel this summer and have had the same difficulties with rough mountain descents. I quickly dumped the sock wheels/cross tires and had a set of wider tubeless rims built up that can accept 40c tires (the max my bike can take). I run those at about 37 psi & that’s made a huge improvement. That, and I’ve been working on keeping loose.
However, most of the time I’m solo & can't afford to take huge risks deep in the woods. I’m probably conditioning myself to descent slowly