I'm from Australia... Central America is not that close
Touché. If you are going to make it a photo-focused honeymoon, take your good equipment and just be smart. At the resorts where I stay, its not uncommon to see tourists with 1-series bodies hanging around their necks, so you won't be the only person there with nice gear. My vote goes for the simple and effective combo of 24-70 plus 70-300. I agree a fill flash is a good idea.
The consensus seems to be to take a telephoto over the UWA, which is helpful to know.
When visiting the jungle with waterfalls, caves, large Mayan complexes, and whatnot - there are ample opportunities to use the UWA. But if you want to pack light, just reply on the wide end of the 24-70.
5D mark 3: R14/2.8, 24mm f/2.8 IS, 35mm f/2 IS, 50 1.2L, 100L macro, 85L, 135L, 300mm f/2.8 ii. 8-15L Fisheye, 16-35L, 24-70L II, 70-200L IS II, TAM 150-600mm, 2x600ex-rt
EOS M: 18-55mm, 22mm
SL1: 10-18mm IS, 18-55mm IS