Second Battery vs. Jump Box

[DUKE]

Hi
I am considering adding a second battery on my '89 V, but carrying a Jump Box seems a whole lot easier. For about the price of a battery I can get a Jump Box with AC and DC outlets. With the proper adapters I can run my AM/FM radio and fishfinder off of it and still be able to jump start my main battery if need be. Has anyone tried this?
Thanx - Duke