To answer my own question in part - at least for wet weather I found this by Kata.
and one by AquaTech and the Shutter hat.
The one above by Kata though it would fit a SLR and may fit a Small MF - and it is a great design for sticking your hands inside - like a car when your inside and it's raining to me would suggest it would fog up and create moisture condensation inside.
All the ones i found thus far are for SLR - I haven't found any for MF or even LF. The others have the backs open for DSLR viewing of the screen which leaves the back open to the elements.
Mist and Fog easily can get in - as well - changing the lens jsut opens the camera up to these elements as well.
And this doesn't answer the fact of what to do in Dry dusty conditions.
I haven't found anything conserning after care for cameras yet.
I did find the Shutter Tent which is a small tent for protecting gear bags which looked interesting enough and might provide a small place to do lens changes. Like a never tent never leaks at the seams or if you touch the material while wet or raining, right?
A larger stand in Change tent might work in remote locations to shoot from - but not in all situations. and limits mobility greatly.
I don't know the anwers yet - but hey - I'm trying.