There are a few problems with this. It's not a bad idea, just a bit large and may be discovered.1.Junk radio that works.
1.solid state flasher relay.
1.old big tool box.
1.Big fat rubber band.
1.used car battery that will still hold a charge.
1.Junk mag mount antenna.
Camo spray paint or the ability to climb a tree.
Install radio and battery inside of big tool box, wire flasher relay on power+ of battery connections. Attach antenna on outside and camo spray paint unit. Turn unit on and make sure unit ticks just like the flasher on your car. Select channel where jerk likes to stay. Charge battery overnight. Locate closest possable drop location by jerk, get really close. Hide unit in bushes or up in a tree. Turn unit power on and select channel. Wrap rubber band around mic causing flashing dead key. Enjoy the three days you have knocking out jerks receive, if close enough bleed over will have taken out all forty channels. Recharge and repeat untill he is a good boy.
This works, ask me how I know!
Using a 100mw or 1/10 of a watt walkie-talkie insures that the only person affected will be the jerk. A 1/10th of a watt radio will successfully jam only the jerk; or do you want to tick everybody off? . Who needs to ruin everybody else's use of that channel when it can be avoided by using a low-power radio up close! If one uses a radio as you specify; one would also need to turn the power output way, way down. If said jerk should find it -likely cause its a large setup- he gets a free radio, a battery, and antenna for his troubles. If he should find a $2 walkie-talkie -which is much harder to do- he has no bragging rights...
Small is stealthy!