It's hard to tell you where to start without first knowing, where you plan on going. In other words, you mention long distance, but what exactly do you mean by that? Do you plan to stay within the USA borders, or do you see yourself heading down the Pan-American highway? I think that most people here would agree that each build will be different, and a lot of it plans on where you live, and on where you're going. Let's take tires for example. Although a nice deep mud tread will work well for rock crawling and looks awesome, it isn't ideal for overland treks due to the heavy weight which exacerbates wear on suspension and steering components, mud tires typically work well offroad but are actually inferior to a good all terrain in the sand, as the mud tire will want to dig instead of float on the soft granular surface, and will also wear quicker on road. A solid axle swap, while awesome in technical offroading, can cause headaches down the road if not done correctly. If you have a custom setup, and you need let's say a leaf pack, or shock hoop, whatever really, it's going to be harder to source these custom parts if you're on some backroad in Guatemala, and they are most likely not going to have that 37" tire that you plan on running. Also avoid putting things on your roof if at all possible. I agree that it looks pretty cool, but in reality it's not advisable to how it affects gas mpg negatively, raises your already high C.O.G. and becomes a PITA when you're trying to pass through some low lying brush. A 35"-37" tire weights on average between 60-70 lbs w/o a rim. All together you're talking about throwing 100 lbs on your roof.
It may seem as though I'm telling you not to do anything at all to your vehicle. In a sense I am, and I will say that I think it's best to take a stock vehicle out and get a sense of it's capabilities and its shortcomings. Once you have a realistic assessment on your vehicle as a whole, then plan your build from there. I know that you said you want a rock-crawler/ overland rig, and some people may disagree, but I don't see the two going hand in hand in a realistic sense. Obviously you can take a vehicle with 35" tires down on an overland adventure, but the point of an overland vehicle is to have something that you know is reliable, the better mpg the better especially if you're talking long distances that gas adds up my friend. the list can go on but, overall I think by rock-crawling you're subjecting your vehicle to alot of abuse that will come back and bite you at the most inopportune time while down the road in some far off country while outside of your comfort zone. Alot of the builds on here are absolutely nasty, and is what attracted me here in the first place, so I'd be hard pressed to say I don't have a list of things I want to do to my car. But at the end of the day if you take anything from this post, just make sure that whatever you add has a quantitative and qualitative purpose. You want to make sure you're not adding un-needed weight (keep the GVWR in mind) and you also want to stay away from anything that will add complexity to your build for no rhyme or reason. Ask yourself if you really need a dual battery system with inverter? Don't assume that because you see a vehicle with a rooftop tent and a lighting system that draws from the hoover dam that you actually need all that. You may or may not, again it's hard to tell you where to start without first knowing what your plans are.
Although that was a bit long winded, I hope it helped out a bit and look forward to hearing what your plans are.
