Jonny...
The answer is yes, it can be done. Any question here sparks major philosophical debate on and off the subject of the original question asked. So among the fluff, some people offer good advice, and at times it is bits and pieces that may be hard to find an answer in, especially for a non-radio type.
What I think you need to know, aside from some of the good info above, is that Wally runs on licensed by rule service, so they use off the shelf radios, like the M you have, and there is no on site license required, no operator license or qualification. I think they also have some real licensed stuff at distribution centers, etc, I did see a large license pop up in a weekly report once.
The UV5R technically does not qualify for MURS use. The rule is there to protect the integrity of the service. Can you use one, sure, it will work fine.
The problem you have is this: You are not going to know what PL/DPL codes you need for which channels unless you can either use a good scanner to decode them first, then setup your radio for that location, which would be a pain with that type of radio, you would have to change it all the time. It's very very unlikely that anyone at the store knows anything about the radios, beyond where the charger for it is. They would not know what a PL/DPL code is, how to find it on their radio, even if they could.
I think you have a very good use for what you need to do. I can completely understand. The limitations of the type accepted radio will keep you from practically implementing what you want to do.
Also, tried to PM you...couldn't. Can you enable a PM or email on your RR profile?
