[Plugin: User Role Editor] Select role while registering

Look at this plugin
https://www.ads-software.com/extend/plugins/reglevel
May be it could resolve your task. From its description:
“You can add a special link through which users can register and have a particular user level/role applied by default.”
This way you can build you own menu or roles list with different links to registration page.

Don’t know about you, but that plugin makes me a little nervous. In the fact (which they strongly read before you get the 1.1 version of the reglevel plugin) they “strongly recommend you use the Role Manager plugin for WordPress.” Well, the Role Manager plugin has not been updated (at least on the sourceforge.net page linked to by reglevel) since WordPress 2.0
Seems a little out of date.

I didn’t test it myself. I just proposed to look on it. As its last update date 2012-03-1, this plugin could work with recent WP version with high probability.
A good practice is to setup any plugin at the test environment first and check how it works, is it compatible with other plugins you use. Then there will be no reasons to fill yourself nervous, even a little.