Definitely a time to make sure you've the sensor cleaning turned on, and are happy changing a lens without pointing the body "up".
How much hiking and stuff are you doing? I guess I'm saying are you worried about weight as you shuffle between bus and taxis, or are you going to be carrying everything on your back for hours?
The days that large sensor sizes really matter are long dead, you can tell this because Pentax have just launched a full frame digital camera. Ok that's a bit tongue in cheek but it's probably true for you. If you are renting and doing lots of active things, maybe look at getting an Olympus or similar if you are renting? The 300mm f/4.0 is considerably smaller and lighter than anything in DSLR space.
I really recommend the pacsafe camera strap it will prevent someone snatching the camera.