If your adult site is simply a portal / front for an affiliate program, don't sweat it.
Just use the basic boiler-plate notices, something like "This site is intended for adults only" ... plus add another statement regarding the models, such as "All models are age 18+" ... and finally a 2257 statement / link (federal law regarding proof of age of models; custodian of records); most affiliate programs provide a 2257 notice / link for affiliates to place on their webpages.
If you're producing content, especially if very alternative, be aware of "local community standards" - selling memberships, products, etc to people located in certain areas of the country can potentially risky.
For more info check out GFY, which is an adult webmasters forum. Google for more details.
Ron