Reselling Customized WordPress Install

Hello, I was wondering if anyone could broadly explain to me the legality of creating a WP installation that is highly customized with themes, plugins, etc. all under the GNU license and then selling it as sort of a Software as a Service product. Is this kind of thing allowed under WP’s license?
Basically the idea is to create a sort of out-of-the-box website, lead generator, CRM type of install.
Thanks!