The connotation is that a full field 43mm diameter is entirely unvignetted. The 2.5" focuser operating at F/7 should accommodate that comfortably. If a 2" Star Diagonal is used, it will badly vignette; their Corrector Groups... you would need to select their second one, designed for full format >>>
"TSFLAT25Del - the big brother of the TSFLAT2. The corrector is designed for full format sensors. The working distance from the M48 thread to the camera sensor is 55 mm. The flattener fits directly to the M68x1 internal thread of the Apos." My guess is that will vignette the corners somewhat.
Once you have the complete system in-hand, there's an easy way to check for vignetting. Make a rectangular thru-hole mask or reticule the same size as your sensor, and place it at the final focal plane. Look through it at a bright wall or sky. Get ten inches or farther back from that mask. Move your head laterally (one eye). You should see the entire exit pupil of the telescope from all locations around the edge of that thru-hole. That's a quick and easy test.
[I quantitatively formalized that vignetting-check approach to certify (giant!) imaging satellites for buy-off and delivery. A painstakingly difficult test. A perfectly/critically-baffled system is a thing of beauty --- and quite rare!] Tom