I've got what I think could be a helpful opinion on this.....but maybe not.
I've got a Land Cruiser FZJ80 and a Dbl Cab Tacoma both are moderately built and geared more for overland use than for rockcrawling. So I can speak from my own experience with a SUV vs Truck point of view.
To get to my answer right off the bat, if I were choosing one, I would take the Truck with a RTT over the SUV. Having used both of mine, there is just some versatility with the truck that is nice. Sometime you just have to haul stuff that is messy or stinky like firewood or fuel or broken parts etc that are nice to just put in a truck bed and not have inside the vehicle with you and passengers. I know there are ways to carry all of that stuff outside the vehicle on an SUV, but I'm just saying that it's been nice to have a truck bed.
The downside to the truck bed is security unless you have a topper on it. With an open bed your gear is exposed to quick fingers and the elements too. But that's why I have a topper for my truck. If I'm worried about security or weather, the topper is on it. If it's not a concern then I can run an open bed.
In either case for sleeping 4 a RTT is the way to go. There is no vehicle except for an RV that will comfortably sleep 4 people inside. With a RTT, you can sleep 4 in the right tent, or put two in the truck and two in the tent.
A big thing to also consider is how long do you intend to be out camping usually. If it's usually just an overnight run then something like an FJ Cruiser or 4Runner might be fine. If it's longer then you need to plan on having more gear which takes up more space and that space can quickly disappear in a 4Runner and especially in a FJ with a smaller cargo area. Which means more of it on a roofrack or tire carrier, or in a trailer which then causes you to reconsider the security and weather issue. On the flip side the larger size of the Land Cruiser has been really nice. Ours is super comfy for our family of 6. Although with all 6 of us gear storage has become an issue on longer trips. That's why I also have an offroad trailer. But if I were you I would look at a Land Cruiser as an excellent option. If you look on expedition portal there is an article written about the top 10 used Overland Vehicles. http://www.expeditionportal.com/reso...-vehicles.html
In that particular article the Land Cruiser took the #1 and #4 spot with the Tacoma as #2. I have a few slightly different opinions about some parts of that article but overall I think it is a very well thought out article and I agree with the selection of nearly all of those vehicles.
Here's my trucks that I'm basing my opinions on.
My Tacoma in a variety of configurations.
My Land Cruiser.
Some friends Land Cruisers. These really are outstanding overland vehicles.