Limited panel depth for radios

I would like to install a Radio in my panel instead of below the panel where it is difficult to see and control.    Most radios are 10 inches in depth.   My Coupe only has 6 inches from firewall to panel.   Any suggestions for a radio that will fit into a standard 2 1/4 cutout and require less than 6 inches depth?    A KRT2-S radio will fit but it is ETSO and FCC approved not STC.    A PAR200B radio is 6 inches in depth but requires a remote transmitter/receiver.   Would appreciate any advice how to select/install a radio in a Coupe Panel.    Jim K.   N87124