I use these BLUE SEA 12VDC SUB PANELS (AMAZON) in both my trailer and truck anytime I need to add more fused circuits for my RADIOS and other 12VDC circuits...
The BLUE SEA SUB PANELS are wired directly to my 12VDC at the main battery bank selector switches.
I also use proper fusing and terminal blocks to feed the DC SUB PANELS as well. All wiring is ANCOR BRAND 4AWG marine cables and using ring terminal hand crimped connections...
I always make a great effort to do things proper for my protection as well as the next owner of my trailers if that ever happens.
Roy Ken