Simplest way to reuse a project on Linux and Windows ?

[kuroi_neko]

Sorry to ask such a simple question, but my problem goes as follows:

I've setup an Ubuntu virtual machine on my Windows7 computer using VirtualBox.
I've installed Qt on both systems
I've mounted my Win7 development directory on Ubuntu

Now I would like to recompile my Win7 builds under Ubuntu with minimal file duplication; especially reusing the .pro files.

My problem is that the platform build settings file name seem to be hard-coded as <project>.pro.user, and I need two different ones for Win and Linux environments.
It is possible to recreate the .pro.user files each time I switch platforms to redefine proper targets. But it's a less than satisfactory solution.

I can make a copy of the .pro file to let Ubuntu QtDesigner create a different .pro.user, but again it is not optimal.

I wonder if one could tell QtDesigner to change the .pro.user file name according to the native system, or maybe use a kind of include directive so that the unix version of the .pro file simply includes the windows version.

I'm sure many people have faced this problem before. Maybe someone could point me to the most efficient solution?