Sounds like you've run out of places to visit, Guyana and Surinam. I suspect that Guyana and Surinam are pretty far down most people's list of places to go.
I have not been to Surinam, but I have been to Guyana, former girlfriend was Guyanese. As you would expect roads are pretty bad and can be wet and muddy. The natural landscape dominates over an almost non existent cultural landscape.
Yes you will sweat no matter what, and if you're not careful things will rot - cotton will not serve you well.
When cycling in hot humid climates I pay particular attention to crotch hygiene, things can get out of control pretty fast in those conditions. This may not be the case with you but I've noticed that any cut or scrape gets infected pretty fast. I make sure I clean and cover even small everyday wounds asap.