I agree absolutely with everything you say Blacksheep - I incidentally got to CEng through the degree route. Whilst the EngC route is valid and I would fight anybody who tried to take it away, some jobs (and to an extent personal satisfaction) require degree level knowledge (mine included).
I have a few academic contacts through my various nefarious activities (the aero departments at Southampton and Bath Universities mainly) and I'll gladly put some feelers out and see what anybody says. I don't sit on the right RAeS committees for this sort of thing, but I can certainly ask the people who do.
My feeling is that given the OU has (so far as I know anyway) little or no aeronautical expertise, the best approach would either be for an existing University who has some distance learning knowledge to do something unilaterally, or somebody to do a collaboration with the OU. In the latter case, the proximity of Cranfield and Milton Keynes brings an obvious possibility to light.
G