Folder And Role Security Question

On our report server I have several folders. I would like to set up security such that a user doesn't see any folders except the "My Reports" folder (I enabled the My Reports site option) and a few other folders I specify. These are a shared folder and the models folder.

Is there a way to create a system level role that by default can't browse any folders except My Reports and ones I specifically grant? I would also like this person to default to having the item level security role of report builder to create reports off of report models.

The only way I have been able to accomplish this so far was to add the user to the the system users site level role and then go to every undesired folder and delete the item level role assignments for the user. It seems odd for the user to have access to every folder then to remove permissions from each folder. Should I create a role with no tasks and then selectively add in the permissions to the desired folders?

I did try creating a new system level role that only had the Execute Report Definitions task assigned and assigned the user exclusively to this role but they could still see all of the folders and their My Reports folder. When I created a new folder the user had been defaulted to item level roles of Browser and Report Builder. I suspect these defaults are what caused the new folder to be visible as soon as I created the folder.

I searched the forum for my question so hopefully I am not causing a re-answer of this question.

Thanks in advance,
Sean