The popular Anderson Powerpole® connectors can be panel mounted without additional hardware by simply cutting a slot near the top or side of the cabinet panel where the cover or shell will hold it in place. That makes it easier to cut since there are only 3 sides to form and access with a saw, nibbler, and file require no drilling.
When possible, I usually gang two sets together. This expands the DC power connection points, saving additional cabling. I can then power auxillary equipment like antenna tuners, audio equipment, and lighting with just short cabling.
The slot for dual power poles is cut 35/64” (13.7mm) wide and 5/8” (16mm) deep. This just fits the groove in the connectors. With two sets stacked, there is just enough room for the matching plug without crowding. Use of a roll pin in the connector body makes it even more stable.