Fogging Windows?

[Mr 5 0]

You may have some moisture leaking into the interior via worn door/window seals or other leaks. Check out everything where moisture could get in. Your defroster should help more than you say it does. Might want to check for clear defroster ducts and that all the hot air is going to the windshild. Also check for good heat.

If all else fails, I would suggest keeping an old hand towel in the car and use that to wipe the moisture off the windshild when necessary. Once the heavy moisture is dried, the defroster should be able to keep it off.
Beats having to pull over or worse yet, having an accident because you couldn't see where you were going.