The GMRS and FRS bands are governed by the FCC and have specific requirements not just for use and power output, but for equipment that is allowed. One of the requirements is that radios used for GMRS service be part 95 certified and FCC certified for GMRS use:
§95.129 Station equipment.
Every station in a GMRS system must use transmitters the FCC has certificated for use in the GMRS. Write to any FCC Field Office to find out if a particular transmitter has been certificated for the GMRS. All station equipment in a GMRS system must comply with the technical rules in part 95.
The FRS rules are just as strict:
§95.194 (FRS Rule 4) FRS units.
(a) You may only use an FCC certified FRS unit. (You can identify an FCC certified FRS unit by the label placed on it by the manufacturer.)
(b) You must not make, or have made, any internal modification to an FRS unit. Any internal modification cancels the FCC certification and voids your authority to operate the unit in the FRS.
(c) You may not attach any antenna, power amplifier, or other apparatus to an FRS unit that has not been FCC certified as part of that FRS unit. There are no exceptions to this rule and attaching any such apparatus to a FRS unit cancels the FCC certification and voids everyone's authority to operate the unit in the FRS.
(d) FRS units are prohibited from transmitting data in store-and-forward packet operation mode.
The FCC does not have a process to self-certify radios, so you can't declare the radio certified. If you have an Amateur Radio license you'll find that the FRS and GMRS frequencies aren't available under that license.
So according to FCC rules, your use of the UV-5R is not acceptable on that frequency.