It's better with a winch but not necessary. I just did my dual battery setup last week. I welded in a battery tray on the oppisite side of the stock one. Then I put in a 200 amp relay to keep the batterys seperate when I want them to be. This is good so that if you go camping or something and you want to listen to music with the vehicle not running you don't have to worry about killing your primary battery. Or if your primary battery dies you can use the second one to start your vehicle.
I run just one battery and I have an warn 8274 winch. It is just a red to optima and it runs it like a champ. I've that wich pretty much maxed out in a couple occations and never had a problem with the charging sys. Also I run just the stock kick alt. I figure if it works don't mess with it, plus it keep the weight down. A battery prolly weighs close to 40lbs.
I use a battery splitter which is a pair of Diodes to keep one battery from killing the other. No switch
to remember to flick. Th esecond battery is out of a Honda gold wing M/C, and has enough oomph to
jump the stock battery when it is dead. I also wired in a Ford starter solonoid so I can jump myself
with a switch. (I leave the headlights on too often!)
The splitter is available at most any autoparts store.