GMS and CMC ratios in Ice Cream
After some more research, I stumbled onto this post. The &quot;standard ice cream&quot; recipe linked from there uses 0.4% of a &quot;stabilizer blend&quot; (8g out of 1950g of ingredients).
GMS and CMC would fall into the stabilizers and emulsifiers category.  I used 7g of GMS and 1g of CMC, which seems to be a fairly common ratio in recipes using these ingredients.
The post itself says &quot;standard&quot; ice cream has 0 to 1% stabilizers and emulsifiers, which at least provides an upper bound:

One can very generally place ice cream formulas and their constituent components within the following ranges:
Milk Fat: 10–16%
Egg Yolk Solids: 0–2%
Nonfat Milk Solids: 9–12%
Sweeteners: 12–16%
Stabilizers and Emulsifiers: 0–1%
Water: 55–64%

The challenge is calculating the amounts of various components in the ingredients that are added.  I can say that I made delicious French Vanilla Ice Cream (with GMS and CMC) using that basic recipe  and the Kitchen Aid Ice Cream accessory.