Hi,
Thank you for the invite on the project. Unfortunately, I do not have design capabilities at the moment. I saw you asked for a custom design.
For your needs I propose to use the Wordpress platform and we can find a fitting theme for it to build your blog on. Wordpress has a strong backend with a WYSIWYG editor, just like you asked. With this option I can help you. So, if you would like to find a theme, that we can edit and customize for your needs, let me know.
If you need a 100% custom design, I cannot proceed further.
Anyway, hope all goes well with the project.
Thanks,
George