Presentations, on your own domain
Presentations is a new service: a demo or a proposal for each client, at its own address under your domain, and you see when they open it.
Choose a base domain, such as demo.yourdomain.com, and add its records once. When you publish a website from Studio, choose As a presentation: it stays out of search engines and the gallery, with no badge. Keep it behind a password or named links, give it an end date, and when the client says yes, Make it a website turns it into a normal website.