Creating page templates

Is there a way to create page templates for certain Buddypress related pages?

For example I have a multisite with buddypress setup where people can register an account and a site. BUT I removed the register for a site options from the register.php that way registered members can register for a site if they want to. To do that they have to go to the “Site directory” page to see the button for registering a site (standard Buddypress stuff). And THERE I need an adjustment: a “register for a site” page. So it can be styled too.

Can this be achieved with a page template or only with editing a file like the register.php?

Thanks in advance,