US CB 27Mhz AM is tried and tested, the rigs are cheap and rugged, information is widely available. Why re-invent the wheel ?
There are literally hundreds of models of transceivers, linear amps and aerials available for peanuts. Range is pretty good on AM, many rigs have USB and LSB too, and in the right conditions have a range of many hundreds of miles.
People who are electronically literate can easily modify some of these radios to gain more private channels, a model that sticks in my mind as easy to modify was the Superstar 360.
http://www.ebay.co.uk/itm/Superstar-360-...Sw~OVWzd0o