Bryan
They do make some very small DTIs, including some very sensitive Swiss made ones (unfortunately they're not small enough to survive being dropped by fumbling nitwits - DAMHIKT !)
which I can well imagine would work in the OP's situation with Forrest's ingenious solution.
(OK, that said, from here on I'm talking to the 'wider public'. Obligatory "soapbox alert" to those with sermon allergies !) :
It's easy to slip into a rut, and imagine the work being rotated rather than the indicators, making it hard to use the elegantly pure "dead centres" concept, as the pure, simple generative element it is. Which in my book makes it 'top shelf'
In the age of CMMs it's a reflex to reach for the high-tech whenever things get a bit hard, and guys like Forrest are living treasures for bringing us back to 'doing what you can, where you are, with what you have'
I wish I had a bit of spare time to knock up a sketch; apart from the value to others, it would be good to have on file...
Maybe tomorrow will be another day
The stiffness of the shaft is, methinks, not very material, given that it's vertical, and the applied force will be almost exactly constant and of very low value.
I can see a fabricated 'bar' made from two flat bars either side of the indicator body - or a slot milled in a solid bar everywhere an indicator is required. For stability, it would obviously be preferable to avoid welding !
When I fabricated a metrology rig a bit like this once, I just used plain brass rod for fasteners, countersunk the (dowel-like) holes, and rivetted it over, like the way some machinists squares were (are?) put together.