adobe illustrator - How do I create a PDF invitation template my customer can edit the text only themselves?

I am trying to figure out how I create a downloadable PDF template of a wedding invitation design that my customers can edit themselves. They will be approx 2 fonts used on each template and the customer will need to be able to edit all text themselves. e.g. change their names, wedding date, location etc. etc.

Basically I want to be able to sell an editable downloadable template. So I will need to lock the artwork and "open" the text so they can edit the text only.

If you think of something like this image. That has artwork that I want to be uneditable and then has text that I want the customer to be able to edit and print out themselves at home etc.