After playing about with it all today, I found that if I use my magnifying headset ... like these ...
... with 1.9X main lens, and also using it's it's internal flip-down set of 1.9X, 'plus' the loupe, looking through them all at a combined of 8.3X, I could get a nice, clear, wide enough FOV image, with them placed at a distance that should work in side the Quanums.
So on a whim ... I searched Amazon for "magnifying headset replacement lens" and after some fumbling about there, I found this:
Amazon.com: Donegan OptiSIGHT Replacement Lensplate: Industrial & Scientific
They look to be the same as the lens in my headset, and those will make a nice fit inside the Quanums.
Note: Diopter is not the same as Power, it seems to be about half of Power (???) according to the detail info in the ad for these on Amazon.
Anyway .... I ordered as set and hope to be able to stack them as per my little experiment ... and as per Reed L suggested above (thanks!!) to get to the sweet spot!
I'll hot glue up a frame to hold them and add the side tabs to move them back and forth ... like the Frensels in the Quanum.
Should be here next week ......