Ok, I've been out for a quick daylight trial using a ToUcam Pro and a DMK21AF04.AS and various combination of T adapter/extension tube and eyepiece projection on an Orion ED80
NP getting focus with any of the arrangements, however I was not able to get an eyepiece to parfocal. It was either not enough inward movement for the eyepiece or too much outward distance required. I don't think this would be a problem with the T-1.25" adapter.
Also there is an issue of getting the camera imaging in the correct orientation with the eyepiece in an easily accessible angle. Using my 2 different screw on T adapters, to get the cameras to image in correct orientation (ie image not upside down or tilted at an angle) I had to rotate the flip mirror until the eyepiece was pointing roughly horizontally. It was a bit awkward but not excessively so.
At this time I'd say I'm onto a winner, but I won't commit myself until after field trials
From my rough trial it appears that the eyepiece and chip viewing/imaging axis are not too different. Certainly there would be no trouble getting a star image on the chip.