Remember many unlicensed users exist on GMRS and legaly run 5 watts. Running a low power node may work in some areas but not in others. This is not HAM FRS users dont care that you have a license.
Use of the frequency bands 457.5125-457.5875 MHz and 467.5125-467.5875 MHz are used by the maritime mobile in territorial waters. These ships may illegaly use these channels when in a US port. See ITU-R M.1174-4 Use of the frequencys 457.525MHz,457.550MHz,457.575MHz,457.600 MHz paired with 467.750MHz,467.775MHz,467.800MHz,467.825MHz are used in the territorial waters of the United States and the Philippines. See ITU-R M.1174-4