Thank you! Thank you! Thank you one and all!! I finally had my light bulb moment.
Reading
@WhiteHighlights post about using the nail polish cases, and
@JCinFLA posts of how she uses her cards; a simple economical solution finally came to me. As usual; I was going about it all wrong!
Stop trying to label the bottles; and just label the location!
I mix differently than JC; in that I don't pull multiple flavors all at once. I pull, use, then return each flavor; before moving on to the next one. So, putting the right flavor in the wrong location is not a concern of mine. Therefore; marking the bottle is not crucial.
I intend to move away from my cookie sheet:
View attachment 753017
and return to my photo boxes:
View attachment 753019
The only difference is; this time, instead of sorting by alphabet (flavor name), I will only be sorting by basic bottle size.
The big revelation boils down to the dividers:
View attachment 753023
I have always used foam core posterboard in the past. It was cheap, readily available, and rigid. I cut it short, to allow as much of the bottle (and label), to stay as visible as possible. This, I could get to the general area easily enough, but I couldn't find the specific bottle without handling 6-8 bottles.
This time, I am going to ignore marking, or being able to read the bottle entirely. Instead, I will make the divider the full hight of the box (taller than the bottles), and place the locator directly above the bottle. It will be just like JC labeling her box lids, or WhiteHighlights labeling the case doors.
If I get a new flavor; it goes to the back of the appropriate box. If I remove a flavor from my stash; that location becomes available for the next new one. If I
buy the flavor in a larger/smaller bottle; I just move the box it is in, and change the locator in the calculator program.
The locator system should be relatively straight forward.
-- Box number
-- Row (designated by a letter; to differentiate from box and space number)
-- numerical location in row
So it would look like: 1-A-1, or 3-G-12. 3-G-12 would tell me at a glance that concentrate
X is located in box #3, 7th row, the 12th bottle from the left.
Sorry if all that is confusing... I have it clear in my mind.

I will post a picture or two when I get it finished (may be a week or so).
Thanks again for everyone's brainstorming! I doubt I ever would have figured it out without all your fresh ideas coming at me. I appreciate you all!!