The reason I use Thunar is that I can configure it as a proper list (too used to the old Mac system 7!), and for the scripting addons that can be applied. I don't run any Windows partitions, so didn't realise this issue. If you install "pysdm" through Synaptic, and launch it as "su pysdm" in terminal, you should be able to mount your Windows partition. I haven't tried it yet; I may have to create a vbox install to test! Then remove pcmanfm if you don't need it. Let us know how you go.
[Edit] Another option is to uninstall Thunar, and go to /.config/openbox/autostart.sh and uncomment the line "# /usr/bin/pcmanfm --desktop --daemon-mode &"; and comment out Nitrogen. That will in fact take you back to a standard openbox install.