Tube Shards learns us howto install Windows to a Mac USB drive without using Apple's Boot Camp.
A ray of hope was the idea of installing Windows onto a blank external disk. Windows is not supposed to run from an external disk but it has been done before. The brave souls who made this work in the past still needed to re-partition their disk with Bootcamp though, something that wasn’t an option for me. It turns out that it is possible to install Windows to a USB disk without using Bootcamp at all.