Wordpress & Concrete5
Any ideas? Thank you.
Anyhow, here's what I'd do: create the static html/css page template or templates you want, then drop in your C5 tags for the C5 theme and create that, and then do the exact same for WP. The nav bar should be the same on both, and if it's not going to change anyway you might consider actually making it part of the template files instead of dynamically generating it (if possible depending on your site structure). That way your css and template files will be guaranteed to be the same.
I have done this for clients and they are fine with it. You'll just want to explain the tradeoffs: it will take you more time/money to build it, and they will have to remember two logins.