Dual Batteries in 2000 Passport

Looking to upgrade my dope whip into an off road monster. Because I'm married, and want to remain so, I am doing this slowly. ;-)

Recently I took out the air box and slapped on one of those fancy maintenance-free filters giving me a little grunt and snarl, perfect for making it through traffic on the way to drop my daughter at the daycare.

Anyway, with the space left I thought, "Man, what a great spot for another battery." I figure it would be practical in our cold North Dakota winters (-35 is common), plus when I get around to adding that M15000 winch I don't want to drain the battery.

My concept: wire these batteries parallel (- to -, + to +) and see what happens.

Questions
1. Will there be any fire, or lightning ?
2. Can my alternator handle two batteries?
3. Other folks talk about isolators and series wiring, but I think this is a little too elaborate. I don't need 4 million candle power on my roof, or to work on Pixar's graphics out on the trail. This will run my rig and someday a winch, correct-o?

Thanks for the help!  

Over 150 Lookie Loos but no ideas? The 2000 Passport is just a re-badged Rodeo. Maybe no one has ever done this to this vehicle. Follow me then, into the future!    

You should be able to do it but a 15000lb winch is Way overkill. You generally get a winch the has the pulling capacity of 1.5 to 2 time your vehicles weight. IMO there is nothing wrong with overkill, but the extra $ you spend on the winch could be spent elsewhere on your rig.  check out OME, they make suspension lifts for Troopers so they may be able to help you on your passport. If nothing else get a BL just so you can fit bigger/wider/more agressive tires on your Hoopty. Good luck man and i hope it helps. BTW i had a trooper and that thing was almost unstoppable:except the engine.  It is RIP now, but MAN did i have some fun times in the ol'86 Super Trooper  
My bumper sticker says "NOT A HIPPIE JUST A WELL GROOMED MOUNTAIN MAN" LoL

You should be good on your battery idea. Just keep them parallel, not in series to make sure you don't hook - to + or you'll make 24V!
As for the winch, I agree it's overkill. Have you looked into Pierce winches? I use their 12K (PS12000). They have winches up to 20K lbs, and for much less than the other brands. I've been running mine a little over a year now with no trouble. I tried a MileMarker, but that didn't last long at all. You could probably get away with a 9K or maybe 12K, but it's always fun to say I have a 15 thousand pound winch on my truck.  

See, I need some help here. I'm not saying I'd ever get close to an M15000 winch, but if I want my wife to think this is a great idea, I need folks on here <wink, wink> to say it is perfect. <end sarcasm>

Thanks for the help. My last question--it won't overtax the alternator charging two batteries, right?

Thanks everyone!