I do not mix products. I don't do anything differently from how I'd do it if my hair was out and free.
So I DC on dry with undiluted AO GPB and leave on for 15 mins. I could use heat if I wanted to but I'm too impatient to just sit put or I'm too lazy to be bothered. I then shampoo that out (I don't dilute anything) with something like Nexxus Therappe. And then I use a moisturizing conditioner (undiluted) (Aussie Moist or AO HSR or Organix...to name a few of the choices I have on hand) and leave on for whatever the bottle says. Then rinse. Then ACV rinse (1/4 ACV in 2 gallons of water + essential oils of lavender and rosmary).
I've never had any problem with not being able to rinse out. If you think about it, braids are like a pair of woven material. When you wash clothes, even if you rubbed a bar of soap over say a pair of socks, you'd not have any issue with rinsing. As long as you allow plenty of water to wash through your hair and you squeeze and squeeze and squeeze as water runs through, you should be able to get it out. You'll know it's gone coz the water will stop frothing.
When I apply conditioner (whether protein or moisture) I take a few braids at a time and smooth the conditioner the way they do relaxer, on a few braids at a time. I skip an inch or so near my scalp and focus on the older part of the hair and especially the ends. I then squeeze the braids to make sure conditioner penetrates the strands, so none are neglected. I then plait those together to get them out of the way, and work on another set. I tend to leave them hanging down so condish can drip to where it's needed most and not down to my scalp where it has no business being. I will put on a plastic bag which allows for the extra room needed for my long braids to hang down. When rinsing, undo the plaits I had put it in when conditioning and just leave the braids hanging down and squeeze bunches of them from the base to ends as water from my shower head runs through them. I do this till no more froth is coming out and the water is rinsing clean.
ACV rinse is done either by dunking my head in a basin of the mixture and massaging my scalp or if I'm in a hurry, I just mix 1/2 my usual in a gallon container and pour it over my head stopping every now and then to give my scalp a good massage, and then pouring over my head using one hand and then using the other to squeeze the brains and just make sure they all get to soak up the ACV rinse.
