Suzy and
to IIS. Glad to see you've decided to become a more active member. Any scope can collect dew and it can cause problems. The idea of a shower cap is a good one, a few people use that and it wont cause problems with keeping dew in. The air can still get around the base of the mirror.
I like to throw an old sheet over mine or towel and they are usually cotton. If I leave a scope outside overnight I'll cover it with a more waterproof cover like a garbage bag but I'll take it off in the morning to allow the scope and mount to air/sun dry