It sounds as if you are close to being able to take the stabilizers off, to use a cycling analogyStill trying to figure this all out

The base mix is not intended to be a complete feed; shop keepers are typically only thinking about complete feeds, and may be rightly cautious about speculating on the nutritional values (or effect) of anything you're going to add to it at home.She didn't recommend it because of the low protein content.
Exactly. I do not rely on vegetable matter for the protein. Animal proteins are better for chickens but they are not normally in complete feeds because 1. they're relatively expensive 2. they complicate the manufacturing and storage processes and 3. in some places (like UK currently but being revised as we speak) they are banned from animal feeds as a blanket measure against the further spread of zoonotic diseases by irresponsible feed companies.supplements with a rotating protein snack
That's great if they can't forage; some fresh greens are beneficial. My chickens prefer to find their own, and have never been much interested in fruit and veg trimmings.I supplement with what I call salad every day - rotating greens
That's the best thing you can do to improve their diet - let them find some of it. Unless you use herbicides and pesticides of course.Question: what can I do better? Ordering some e fence to get them out to forage.
I've come to the same position.I have never discussed my feed choices with the place I buy it from currently but the stuff I use as scratch I decided on after my own research and much discussion with the owner of an old feed store
That's the trickiest bit.finding a local seller of that feed
That's great if they will, and warrants supporting same store when you can so that they are still in existence next time you need them.Sometimes a feed store will order in what you want
That's where a complete feed is convenient.I do need to be able to leave them occasionally