Water is all I use.
Even 4th rifle, it’s no issue to drop trou and hang my ass over a trickle of water and wash butt and balls daily. Early seasons I’ll splash water on my face and upper body. I’m not worried about how I smell, but if I’m packed in for multiple days I’m washing for hygiene and good habits just like I do backpacking. Just because it’s backpack hunting, it doesn’t need to be some kind of combat endeavor.