Naming Ceremony Invitations Paper Names On Response Cards?

Names on Response cards? - naming ceremony invitations paper

We are a small wedding (only about 16 invitations) and I'm the invitations. Instead of M_______ in the reply card, I wanted the names of persons they are subject to write? You may write the name, as they are in the outer envelope?

Also another question. The ceremony will be outdoors in summer, but the reception inside. How do I know what you can put right? Should I slip into a small piece of paper saying that "time permitting, the ceremony will be held outdoors. Please dress accordingly."? The invitations were, and say no extra space in this country.

Thank you!