that's a cool idea. I like imagining how it popped up in your head.
Do you happen to know at what eccentricity both stars are towards each other in their current stage of 42 years orbit? I mean, was it easier to split them 10 years ago than it is now?
Wiki on
Procyon says they're both lightweight suns, A at 1.5 solar masses and B 0.6.
What would it take to measure how much the path of the photons from B is warped by the curvature caused by A? Your crosshair blocking out A's photons must be the valuable first step towards that.
That they're difficult to split right now could indicate that they're in the best orbital position to "see" that effect, if it can be made visible.
This double star may well be too lightweight a test pair. But in theory, with a pair with a heavier dominant A, how would you make that visible with your powerful C11...