Site Assist Professional is not compatible with DW CS6.
Surveyor is not a site creation tool, nor is it included in Design Extender, the site creation tool in design Extender is Site Sculptor.
In Site Sculptor, you can use your own custom template to create a site design.
You could use CSS Sculptor to create your design using the Nautica Color Scheme, then create a custom Site Design using the preset manager.
See the "Creating a custom template for Site Sculptor" tutorial on the Site Sculptor support page for more details.