You don't need to go to that much trouble.
You can make an install of the base RBR first. Then copy that RBR folder to a new location on your HD (just rename it eg. RBR Czech) and use that for your Czech Mod install. You may then have to delete the original install to clear the registry.
Then you can make a new installation of the base RBR for the RSRBR2012 install.
The only thing you may have to be careful about is that when installing addons etc to the Czech mod, you may have to point the files to the correct location.
There may be other ways to do this, hopefully there are others here who have both mods installed, who may post advice.