The scope of this project sounds huge. I'm not exactly sure what you are looking for. It seems that you have more than 12 websites that you want to have optimized.
I would really need to see the sites, know how they are written, what access there is to them, languages, etc.
An ongoing project like this could easily exceed $3,000 monthly.
I do have a writer and other coders that I can utilize.
Please see my profile for examples of my work.
I have been optimizing websites since 1997, long before the term SEO was even coined.
I am currently working on my own in a solo SEO career.
--Robert Kelsey