That 500w amp draws only 80 amps peak, you don't need dual batteries and all those other parts to run it as a normal ham radio amp.
The winches many of us pull way more amps than that. A typical winch can easily pull well over than 400 amps on a heavy pull and over 100 amps on just a standard pull... and we get along fine with single heavy duty batteries and the factory 117 amp alternator.
Not to mention it'll only pull that 80 amps when it's transmitting at max peak power. Not something you'd likely much much in a Jeep.
And I'm no stranger to running high power HF rigs up to 1kw.