Hello umbraco community!

I have a question regarding the umbracoUsers table in the database of my umbraco ASP.NET MVC project.  I'm using umbraco version 7 for this project.

Here is the issue put simply:  I'd like to create a new type of administrator for my site.  I don't need this administrator type to have access to the Umbraco backoffice, actually I'd prefer to not allow that.  However, I would like to enable them to log into my application through my own admin user interface that references accounts from the umbracoUsers table.  I'd like to restrict access to certain parts of my admin portal for these users, while granting access to a specific page that will be used for voting on issues.  A full-access administrator will then be able to process the votes.

I was thinking about approaching this by adding a bit column (limitAccess) to the umbracoUsers table, and evaluating that field in my application to determine what parts of the site they have access to.  Is it safe to make this addition to the umbracoUsers table, or should I create another table that references the umbracoUsers table ID column as a foreign key and sets permissions from there?

I hope this makes sense!