Well I have never had this issue with my mirror cameras as yet, but there is an interesting article that "may" help....attaching the link below. I don't know when the article was written or if the camera access by pulling down and out the small convex mirror above the camera will work for all typical RV mirrors (read this as owner may wind up with a broken mirror if you try it)......but some info may apply and be helpful. If you do get into the mirror and get the camera out, let the forum know how you did it. Good luck.
https://rvnstyle.com/fix-foggy-rv-si...with-pictures/
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