Someone posted an idea of using T-channel that captures nuts for mounting the radios. I can't find that original post. It allows the radios to be re-positioned easily without having to drill new screw holes; just loosen the screw and slide the radio and tray up or down.
Here is how I implemented his idea.
Installing the channel
http://www.mykitlog.com/users/display_log.php?user=sdahrens&project=248&category=9948&log=222457&row=33
http://www.mykitlog.com/users/display_log.php?user=sdahrens&project=248&category=9948&log=231424&row=11
Radio trays in place
http://www.mykitlog.com/users/display_log.php?user=sdahrens&project=248&category=9948&log=240176&row=7
Just one of many ways to mount the radios.