People are riding loaded WR250Rs at about 65 to 70 MPH all over the world. The motor will rev all day and has a 27,000 mile valve inspection interval. It is based on the R1 superbike engine (1 cylinder) . It lacks torque, but loves to rev. My setup would have a 4.7 gallon tank and get about 60 MPG. This engine is known for extreme durability. It wouldn't be ideal out of North America though because it wants high octane and is fuel injected. It would be lacking in grunt, especially at elevation. My camping gear is mostly for bicycle touring, so other than gas and water, relatively light. The rental Suzuki DRZ 400 was really nicely setup and might be preferable. It is quite torquey, but flat when revved and feels heavier in single track. Not the greatest on the highway. Also known to be bullet proof. Most adventure bikes as currently marketed are going too heavy with too much horsepower to be good off road. On dirt roads, they want to go way too fast. If you tip them over, you risk a hernia trying to pick up a 600 pound bike.
Renting this bike out of Grand Junction Colorado, then driving to Moab and around the White Rim trail was about as good a mini vacation as I have ever had. Again, blown away by the Majesty of Colorado and Utah. You feel pretty alive knowing you can fall off a 1000 foot cliff at any moment.