PortableApps Overlay DE?

At my school, the computers are locked down to the point that most of the Windows customization is disabled, and their network policy states that if students install ANYTHING on a computer without an administrators written consent, they threaten to suspend or even expel students. That's why I use PortableApps.com.

A few of the things that I am not allowed to mess with that bug the crap out of me are as follows:
- Desktop Background
- Pinned Applications
- Taskbar Icon Size
- Taskbar Autohide Setting

There are several other things as well, but these things bug me the most as it feels like they are actually obstructive to my workspace, plus all of the other nuances are avoidable by using PortableApps.com apps.

The desktop background that the school forces us to use is ugly and repulsive. This is not a huge deal as a often have a window open that covers it up anyway, but if there was some way to change it that would be nice.

Luckily they do allow me to change the theme settings, so I can set it back to the Windows Classic theme which uses less resources, and takes up less space than the Aero theme.

I am used to working on a 1920x1080 screen, so many of the school computers feel very cramped in their 1600x900 or 1366x768 environments. As if the lower resolution isn't bad enough, the school district locks the taskbar down so that is takes up a ton of extra space and is not autohidden, none of which I am allowed to change.

And finally, the pinned applications. I hate IE and Windows Media Player, and would much rather use Firefox, and VLC which I load from my PortableApps.com drive. What annoys me is that my school district forces me to have the Windows 7 default pinned icons in the taskbar. I am not allowed to unpin the applications, so I have to constantly have to look at a giant IE and WMP icon in my taskbar when I am trying to work.

What I am wondering is if there is some application that I could run off my PortableApps.com drive that would use some sort of fullscreen overlay that would essentially act as a replacement Desktop Environment / Window Manager to the normal Windows Explorer. Something that uses it's own task manager as a replacement to the task bar, and I can change settings, without messing with the computer. The first thing that comes to mind is MojoPac, an old solution that ran basically a virtual Windows profile from a flashdrive, using the Windows classes on the host computer. It was really quite cool, but it only worked on Windows XP, and doesn't really exist anymore.

What I am wondering is if there is something like MojoPac that works with Windows 7, or some other similar software.

If not, what would the implications of a software like this be, if it is even possible, would it be viable?

Sorry for the long post... I wanted to describe my situation before I made my request.