pay to post to custom post type and custom taxonomy

Hi
I am looking for a solution to a problem I have and hope that this plugin (perhaps with modifications) may do the job. If it does I will sign up for the support package and extra help.

I need to have the ability for users to sign up to a membership level that allows them to create one post, and then demotes them to a lower level once they have submitted this post. (Perhaps another level offers them the option of creating five posts if this is easy to do.)

The post they are creating is a custom post type with a choice from of custom taxonomies. Do users have access to the backend with membership levels, or only the front end?

Is this possible to do with this plugin, I have been searching for something that would work so any suggestions gratefully received.

Thanks.

http://wordpress.org/extend/plugins/paid-memberships-pro/