Few points:
1. A rear bumper and tire carrier sound cool, and look cool, and work well offroad. Day to day, mine is a pain. I'd put it last on the list of things to do.
2. Benc is correct. A real bull bar will help you a lot in a crash. I have some real world examples, from my father in a 1997 4runner with several ARB bull bars (Kept replacing them after the crashes, and also in his 2004 Tacoma:
a) Dad and brother are out on adventure together a few hundred miles from home. Old man in a buick turns left in front of him while he is traveling 20 mph. Bull bar is bent, fender is dented. Buick roof is seprated from the b-pillar to the rear glass. Accident report, blah, blah, and after, they loosen the bolts on the bull bar, pull it back into semi shape, tighten it back down, and drive off and continue their adventure canoeing and camping. Zero radiator damage, no headlight damage, no hood damage, nothing to make the car unsafe. Got it fixed under insurance when the got back.
b) Dad again. comes around a blind curve at 45 mph (the speed limit). BMW X5 stopped in road looking at big horn sheep (sheep are not on road). rear ends BMW. Again, bull bar bent and mangled, but no body damage, and no damage to the workings.
c) Dad and mom in 2004 Tacoma with ARB bull bar (again). 4wheel camper in back, headed up towards Banff NP. Not long after they cross the border into Canada, they unfortunately hit a deer traveling at 55 mph. Bull bar damage: Broken turn signal, slightly pushed backward.
Now, I will argue that a Moose is a bad example. I have a reasonably lifted truck, and I would imagine that if I hit a moose, bull bar or no, its coming over the hood and into the windshield. Doesn't really matter what you have on the front at that point.
3. I would get a light bar, as the extra light is VERY nice on the long highways, but I wouldn't put it on the roof, unless you black out the hood. I've been in two truck with roof bars and the one without the blackout hood had wicked glare. Would be very distracting on the road. I have my lights wired up to my highbeams, so when the big lights are on, I can simply hit the dim switch and they go off with the brights. Very nice for driving on the highway.
4. Sliders are good. Good piece of mind. Personally I keep them tucked in as tight as possible so that you aren't constantly getting mud on your pants when you get out.
5. "full skids" aren't really needed. I've seen tons of trucks with full belly pans and I've never seen it be usefull. A good front skid under the front diff, a tcase skid, and a gas tank skid are all you need. The full skid pans hang down and you actually lose clearance in a bunch of areas. My advice would be to just do the minimum on skid plates. I honestly don't see you needing them whatsoever based on the type of trip you are talking about, as you have factory skids on those things which will survive quite a lot (I beat mine to death before building new ones, and I was taking it up more difficult stuff.
Anyway, its obviously your truck, and if you have your heart set on all that stuff, go for it. I'm a firm believer in building the rig you want, not what the internet thinks you should have. My $0.02 is here just for a perspective. Best of luck, and congrats on getting to take your son on such a great trip!!!