Here's what I do, maybe you'll get an idea that could help.
I didn't stop shampooing all at once. Once every 2 days, then once a week, then once every 2 weeks, and so on. That was decades ago, I didn't know I was going no-poo at the time. I just sort of weaned off.
I've used shampoo a handful of times over the last decade when something really unusual happens. It's a huge difference in feel. Some people say they couldn't get used to the greasy feel of no-poo. I think it's just a different feel. Now I can't get used to the feel of shampooed hair! It's kind of like dry skin, sort of itchy. And I can't do a thing with it! lol
Layering my hair helps a lot. When it's nearly one length WO doesn't get to my scalp and I'm left with more gunk than I'd like.
Imagine one of those old mops with all the thick strands. Think of how it would be to wash it out if it was head up, compared to dunking it in a bucket. That's how I wash my hair, bend forward, in a 5-gallon bucket, or I use a garden hose or the bathtub faucet. While still bent over, I gently squeeze it out, comb it, then (still bent over) put it in a flannel pillowcase. I use the elastic from the waist of an old pair of sweats to band it in place. Sort of like scrunching.
I can't use a brush, my hair is too thick, long, and wavy. I use a wide toothed pick when it's wet, then pick or finger-comb it when it's dry.
Now that I write it all out, I guess I'm a bit odd! Hope something helps!