Where are you starting from?
How are you getting to South America?
What is your route in South America?
What bike you riding?
In no particular order:
- Leave the table and inflatable chair at home,
- Forget axes and knives and a separate can opener, get a small Swiss army knife with a corkscrew and can opener if you drink wine - or if not, a Leatherman tool with a can opener (I don't carry separate pliers)
- Take apart and re- assemble your bike at home with only your bike toolkit, make sure you are carrying every tool you need to fix flat tyres, do oil changes, valves, remove starter motor, spark plug(s) - don't carry tools that don't fit or you don't need!
- Don't bother with those stackable water containers, use a Nalgene bottle or a flexible bottle you can roll up (MSR dromedary) - or a hydration pack.
- probably wont need a compass if you have a GPS or a cell phone with a compass on it, if not the small button compass' is probably OK unless you are planning on riding across remote desert pistes or the Salar de Uyuni.
-Use a couple of Bic lighters instead of the firestarter, you can get them anywhere and you wont be faffing about trying to light a fire or start your stove.
- Use stainless steel pots, cheap aluminium non stick pans will last 5 minutes before you scratch them and the coating comes off, stainless pots can be hammered back into shape, you can clean them with a hand full of sand or scotch brite when you weld your pasta sauce to the bottom of the pan.
- Those bungee mesh nets are great for losing things off the bike, buy some proper straps with metal buckles or Roc Straps.
-You will be able to use the hammock in the North, but down South there are no trees and its too windy, good for chilling out on the beach though - when there's trees.
-Wear good quality ventilated leather riding gloves, not cheap textile, if you slide on asphalt and put your hands down wearing those gloves on you will not have any palms left - been there, done that, its not fun
Id add:
spork or something to eat with
small bottle of dish soap - also handy for changing stubborn tyres
sunscreen, insect repellent and after bite
small compressor and/or hand pump
tire repair kit
I also always carry a small container with salt in my cook pots, it is handy for a multitude of things as well as putting on food
Hope that helps