When I hear "overlanding" i see a couple friends loaded up with whatever it takes to get them from point A to B useing as many trails, dirt roads etc as possiable. Is it meant for all vehicles? No. Can a fairly equiped Jeep do it? Yes. Can a LR3 with all terrian tires and some recovery gear do it? Yes, but it wouldnt be able to go everywhere. Can Eddie's Jeep go to every square inch of N. America? Doubtful, but I think he has a good shot and would be willing.
I agree that the people who claim they are "overlanders" only and wear the floppy hat, sandles (with socks!) cargo shorts, and some sort of button up thin shirt are very snob-like! So what would it take to convert them into just being an adverturious off roaders like most of us? I like rocks, I also enjoy the easy routes of gravel roads to a certain destiation. I enjoy snow, fire roads, simple two-tracks thru fields, and even mud...till clean up!
