Signup form on subdomain

Need to fix my mind. Wondering if it was possible to use signup.mysite.com/signup for all the registrations. And mysite.com for marketing and presenting my site.
This way I can install a single page with a custom theme in signup.mysite.com and another theme in mysite.com.
Ideal to separate the registration process from the main site and at the same time make the sign up page working.
Because my main site is a premium theme using a slider so the sign up form is causing a major issue with the home page if installed on mydomain.com/wp-signup.php