I have seen display backs for vintage watches by Rolex and Omega on offer from
Custom Watch Concepts in Germany. The idea is to keep your original case back
for the sake of returning your vintage watch to its original form, but to be
able to enjoy viewing the movement with a display back. The movement is as
well protected as the dial would be. Surely a solid caseback offers better
protection to the movement, but as long as the glass back is not compromised
(including a strong seal/attachment to the bezel), I see no reason why not to
have and wear one.
Here's the problem: I doubt Custom Watch Concepts would create a one-of-a kind
display back for your IWC. I do not know of anyone who would. And
just in case you were thinking of having your existing case back modified, I
strongly urge you not to do so. You'll never be able to "undo" the original
state of the watch, an important consideration.
I enjoy seeing the movements of my watches too. But I am satisfied with
photographs of the movement. I don't want to introduce debris into a movement
by unscrewing or popping off the case back to see the wonders inside!