I don't think you are an idiot, unless you think there's a single best answer that we can give you to the question
For some folks the rig plays a supporting role, staying firmly in the background of the adventure while for others the rig is a leading character and companion through the adventure. Do you know which describes you? If you just want a solid platform that doesn't distract from whatever you are getting into then I wouldn't recommend the 80 or the 4Runner but would echo the more recent truck as a better starting point. If your excitement levels shoot up when you visualize taking one or either of the 4runner or 80 to far-flung places then you may be well positioned to make that happen and be ok with the costs that will be required.
Do you think you'll travel solo or in groups? This can have a large impact on security considerations, the types of places you stay, where you spend time (inside, outside the rig, in camp / other, etc.) and ultimately what type of rig you want.
I drove an '87 IFS 4Runner with the 22RE for years and currently enjoy my '97 LC so I have direct experience with both. I also traveled full time for more than a decade in an 80s VW Vanagon Westfalia, including some time in Mexico, all over the US and a lot of Canada. Over the years I travelled solo a lot and also with friends who were in a variety of rigs. I've seen folks have successful trips South of the border with just a backpack, on bikes (pedal and motor) and in rigs/campers large and small so either rig you are considering is totally doable and relatively secure/comfortable, at least compared to the bikes/tenters.
In my mind both the 4Runner and 80 are best suited for use as "live outside" types of rig where you may cook on the tailgate, often sit/eat/etc. outside, and all of that. You could certainly hole-up in either if you get caught in a long rainy period or as you traverse less secure areas where you need to minimize visibility but both could get cramped depending on how they are setup. A pop-top on a 4runner, if well done, could make it more comfortable for inside living but may make it less secure and more visible also. I assume the 4runner pop-up would have canvas sides where it pops up which doesn't do a great job of blocking noise and is easily cut.
For how I'd travel, which would include the option of going solo whenever/wherever desire struck, I'd want to have a low visibility/profile rig that included comfortable inside and outside living setups. I'd prefer good parts availability and local support since repairs can be tricky in foreign places. Any Toyota should be pretty easy to get parts for, if you can wait on shipping, but I think the Toyota truck platforms from the last decade or two would be the best supported as you travel. I'd lean towards the 80 out of your two listed options and would intentionally make it look as old and bland as I could, cosmetically, so that it was pretty much invisible wherever it was parked. Many folks think my 80 is an old 4Runner so I think it could be pretty stealthy without lift and lots of shine/accessories/etc. The RTT could be great when camped on the beach and in nice areas but I'd make sure it wasn't shiny when popped down and I'd have an inside sleeping arrangement for streetside stealth camping in cities/etc. I'd consider having nothing on the roof at all except maybe a simple cross-bar setup for surfboards/similar that could be stashed inside if the 80 needed to be parked streetside unattended for a period. It can be a little worrying leaving your rig unattended when you want to stay in a hotel/similar, or need to fly home/take a side-trip for a bit, etc. and nothing on the roof could make it possible to get it into covered parking, etc. so could be essential in those situations.
I over plan and am pretty conservative in how I approach "adventure" but have had few issues over the years as a result. To balance I think it worth ending with the observation that so many folks do well on big adventures without all the planning, prep and gear. A positive attitude overall, quick thinking/resourcefulness, a little luck and most importantly the ability to connect well with other people are all you really need to succeed at some big adventures.