Changing lenses outdoors?

[Pelican]

What is the safe and effecient way to change lenses while shooting outdoors? Even in the best of conditions, is it advisable? How about with a bit of wind, and worse blowing snow?

The ND filter protects the CMOS chip, but the filter still may get dirty.
Is the ND filter easy to clean or possibly even replace?

Using a changing bag would take forever, and is it feasible (how would you see the alignment/witness marks on the lens and camera?)

Any suggestions?

 

[Alpha Beta Omega]

Find some place to shield the camera from wind and moister while changing. I wouldn't change in rain, snowfall or sandy environment unless I can make sure nothing enters the gate.

 

[klon]

I would imagine you would run into far fewer issues brushing the ND wheel than you would the sensor. But I'd be hesitant to use air, as I don't know how good of a seal there is between the wheel and the sensor, and I'd hate to blow dust BEHIND the wheel where it would be completely inaccessible.