I am a professional web developer that currently works full time doing just that. Recently I decided I wanted to expand my portfolio and do a little freelance work. I found an ad on Facebook for a local small business looking for a web manager to work part time on their site. I put in my application and later received an interested email back as well as a number that I was asked to text to follow up and set up and interview as the person was leaving the office. Due to my full time job hours being difficult to work around we decided to just do a FaceTime interview as a preliminary before later doing an onsite one if it goes well.
I was then asked to look through the website before the interview so we would be able to discuss what direction I would like to take it if I were hired. While looking at it I immediately saw large design changes I would like to make so I am considering doing a few quick mock ups and emailing it the interviewer so they would have a visual aid for the upcoming FaceTime interview. However as you can tell this is a very informal very preliminary interview. Would it come off as going to far or trying too hard or something like that to do that work and send it before the interview? I don't want to turn something that started as an informal critique of their site to a complete rewrite before they even hire me.
Note: It would not be much/hard work for me, I would actually enjoy it. So I'm not worried about the potentially wasted time, just how it will come across.