The problem I have had with this scenario is button pushing and inability to follow even printed directions. I sent some CERT guys out with 4 5rs and all but one had the channels changed, one even had things erased from memory. The instructions were simple, here is the volume, and push this button to talk. I also loaned out my pair of 888s thinking "no display, no screwing around". Wrong. The non-hams among us simply can't not fiddle with the knobs, even after being told not to turn this knob.
The other problem has been apathy. I gave a buddy a radio who lives 7 miles away and tested it. It hit my tower easily. First phone call from him was about it not working. Took just a minute to get him back on frequency. Next call, ice storm in 2014. I asked why he wasn't on the radio: Oh I forgot to charge it. Power outage 2 weeks ago, he can't even find what he did with it.
My point is, if folks aren't interested in radio to begin with, there isn't much hope of them working when you need them to. Initially it's a new toy but I have found 100% of the time interest and fascination wane and the best thought out plans go out the window.When you talk about giving the general public a radio and asking them to do more than push the button and talk, it is truly a recipe for disaster.
There is nothing wrong with your plan, or using Boafeng radios, or even your channel scheme. What you will find wrong with it is people. I do wish you luck and hope your experiences are better than mine.