Oh it'll definat;y make it. I personaly have no issues with my seats but I could see that being an issue. Take spares, specificaly, a Spare alternator, new belts and in your case if you're gonna wheel it at all and have 33" or bigger tires, get good at changing the Birfield joints... THese trucks will go ANYWHERE (more so with yours being a SFA model) and frankly they're built tougher then alot of 1/2 ton trucks out there these days.
If the truck's in sound working order adn you're not going to be hauling more then 2 people (this is a big one) you're fine. My GF and I frequently take my truck out for weeks on end and aside from wanting an Aux-fuel tank and a Water tank it hold more then enough gear for us to live out of it for I'd guess up to a month comfortably maybe a little tight if we had no access to water and fuel, but then that can be gotten around in some ways too...
If you go to larger tires, I'd highly suggest re-gearing. I'm doing OK with my 33's and 4.10's but BOY can I not wait to get the 4.88's in there. It will make a world of difference and get your fuel econ. back as well as the use of 5th gear. PLus you wont have to climb every steep grade in 2nd gear (that get's annoying)...
SO to answer your question: "1ST Gen 4Runner Overland..." YES. It's an older Toyota it's built better then 99.9% of anything that's out on the road right now.... Go for it mate, and take LOTS of pictures
Cheers
Dave