This would be a large and heavy solution.
Instead why not get a single desktop or single U rack mount server (or even a decent laptop) and setup VMWare or Windows Virtual Server on it and setup a few virtual machines. As far as the software knows they will all be on thier own hardware. If you were to use a laptop it would be ultra portable as it would only weight what ever the laptop and bag weigh. With both products the virtual machines just run in the background and the desktop looks basicaly normal except with some extra software installed.
We currently do this for our development systems and will shortly be doing this for our production servers.