Lots of naysayers out there.
The US Aircraft Owners and Pilot's Association magazine this month has an excellent article on a private pilot who did just what the original poster proposes; flew all over the world in his private aircraft. Including antarctica, and Iraq.
Bob Gannon did 2,200 hours and 1,200 landings in 155 countries in the space of a little over a year in an older Cessna 182. He had a little more endurance in fuel than the original poster proposes; he had 22 hours of fuel on board.
You can read some of the trip at
AOPA Online: Oh, the places you’ll go!
You can visit Bob Gannon's web site at
Welcome to World Flying Adventure.com!
Before you spend too much time listening to those who have never gone abroad and do nothing but decry the possibility, visit a site which features those who do know what they're talking about, and who have; the Earthrounders:
Earthrounders: round the world flights in light aircraft