Officiant?

My FH and I are planning on our wedding being very personal, meaning that only people we are extremely close with are being invited. That being said, we asked FH’s grandpa, whom we are extremely close to, to be our “officiant”. In the state we live in a notary can legalize our marriage, meaning my mother will be doing that so that we don’t have to put his grandpa through the whole process of that. We aren’t too keen on the traditional vows and we’ve decided to read our vows together in private before our reception. We’re struggling with what to have his grandpa read/ say and what we’re going to do during the ceremony. Any ideas?