Default Attachments -- I want to attach certain files on every proposal

Every single project, I attach my contractor license and my proof of insurance. This wins me projects because it builds trust with the client. Re-attaching these files every time is a pain, so I'd like to set it and forget it. I also have a files I may attach to every job if I had a feature like this. It may be a company brochure, a pdf with past reviews, an about-me of our company, etc.