Best setup for SEO on multilingual - multidomain Wordpress site

Here is my dilemma:
I need to setup a bilingual site using WP (wordpress) - I want to optimize the structure for SEO, so that each domain name's keyword would have a positive impact on my SEO efforts. I also want to be able to manage everything through one single WP install, and possibly have a way to create 2 posts in each language through a same dashboard view.

Example:
french domain: maisonsenkit.com to be used for various SEO on terms related to "maisons en kit" keyword
english domain: kitconstruction.com to be used ....terms related to "kit construction" keywords
the sites would have almost symetrical content but in a different language.

I was looking at WP multiuser plugins like wpmudev.org's WP multi domains or WP domain mapping, but to be honest I am rather unsure if it does what I need nor which one to chose - let alone how to configure the MU to make it work.

Anybody understands how this could be setup to fit my needs?

My main concern is SEO...

thanks
~F

PS: I do have asked some questions to the WPMUdev support team but no conclusive answer has been given to me...