Multisite and WPMU Pro Sites Question

I am looking at creating a site network using Multisite and the ProSites plugin.

Using ProSites I would like to allow people to pay for and build their own site on my network. The trick is that I want them to have a very simplistic user interface. I have found plugins to limit the menu items available to the Users. For content creation I am hoping to have the Users basically fill out a form. That form would connect to the content areas on their 1 page website to create the content on their page. The form would also contain areas where they can submit images and possibly modify the background colors of their site.

Is there a plugin that will support this or will I need to develop a custom theme to make it all work.

Any insight is appreciated!