A bit of a different tack - for the mirrors, I found that when I made Scott Tannehill's
fan modification on my GSO 12" any dew problems stopped. It directs airflow from the primary fan across the face of the primary and up the tube. Improved seeing as well. I didn't even do the full mod just put the baffle over the end of the tube with a hole cut over the fan and some 1 cm thick foam tape around the internal circumference of the tube just a tad above the primary. If you have a truss dob, you'd have to use a shroud to get the airflow up the tube.
To stop my finderscope fogging up, I just put the caps on between looking for objects and a little plastic bag over my red dot finder. Takes half a mo' to take them off when star hopping.
Peterbat made similar mods to his lightbridge after a dewy session at snake valley and told me that he also got very good results.