If there is the possiblity of AC power available you might want to combine a power supply and adevice like this one:http://www.dxengineering.com/Parts.asp?ID=716&PLID=158&SecID=70&DeptID=23&PartNo=SAR%2DPOWERPANEL+UPS
To keep the batteries charged for use & power the radio when AC is available.
Also i would resis cutting into the side of the case for the radio. Instead consider making a plate that would fit in the box under the cover with the radio face sticking out, along with some ventilation to let out the hot air that will be produced by this radio & other equipment. A pelicam case may be over kill actually. You might want to look at a large plastic tool box. I have seen some nice setups built into these.