My friend and I spent three days camping at the Marianne Beach Resort. It is located right on a beautiful beach, and a hike of approximately half an hour from there would lead you through a wonderful rainforest to spectacular Paria Bay (just be prepared to walk on muddy trails if you're going there during the rain season).
The place is nice, and Lenard was very welcoming and helpful. The campsite is cheap (100TT) and we were not charged for the use of washrooms, kettle, phone charging… so no bad surprise here!
Be advised that there is no internet here, and no ATM in whole Blanchisseuse.