Buy or rent a telephoto lens for my 60D

I'll throw out another option - Tamron AF 70-300mm f/4.0-5.6 SP Di VC USD XLD for $349 after rebate ($100) from Amazon. I have it and am happy with the results. Have used it with a Tamron 1.4X teleconverter with good results. Has gotten good reviews from other users on dpreview. If you have a longer zoom, you will find uses for it after your trip. Even for very occasional use it doesn't cost much. Happy with mine.

Steve W.