Does it make sense to have a fullspec or standard sub-folder for the object files and binaries? Usually (and this might even be required) you run would run "make clean" before re-building for a different board type anyway. And usually your Pi is either connected to the one or the other board type, i.e. it is unlikely that you need both binaries anyway.
Unless I am missing something this sub-folder should be removed, so that 'bin' and 'obj' are located in 'cpp'.
Do we need support for 'standard' at all? The Wiki indicates that this kind of board might never have been tested.