The kind of fogging that you describe sounds weird, but I suppose within the realm of temperature changes. I've never had a lens fog unless I went into an obvious humidity/temperature change. And I've never had the inside fog up. I always thought that the sealed air pocket prevented it. Maybe your lens is damaged and no longer sealed? That might explain why even a bit of humidity caught inside the lens would cause fog against the outside, and why it would take so long to defog. I'd get your lens checked out.

Otherwise, I was just at a conference this past week where several very successful photographers spoke. They mentioned fogging briefly, and they said a good trick to defog quickly is a hairdryer. I wonder if you could carry around a battery operated blow dryer?