Even though CB's are generally low wattage, consider that if you do have it encosed anywhere some amount of heat will build up - does it matter I don't know, just that any radio will have some heat.
So have you considered simply mounting it up next to the side of the console, slightly ahead of the drivers seat. If that doesn't work for you, how about some way to remove the push in and out cupholder - if that model has them and maybe it would squeeze in the dash with some room around it?
Two years ago I needed one and ended up buying a handheld Midland 75-822 unit and put an extension w/magnetic antenna on the roof.
The battery comes off when using the 12v power connector.
That leaves a small handheld speaker/mike connected to the power cord (plugged into the rear facing 12v outlet at the back of the center console).
When I need it it just sits in the console tray, if not I disconnect and stow it.