Scripts are loaded in the following order:

    $XDG_DATA_HOME/nautilus-python/extensions (i.e. ~/.local/share/…)
    nautilus_prefix/share/nautilus-python/extensions (i.e. ~/Development/…)
    $XDG_DATA_DIRS/nautilus-python/extensions (i.e. /usr/share/…)

Simply copy your Python scripts into one of those directories and restart Nautilus.