Sand is good for drainage and for easy root penetration. But it doesn't hold nutrients. Clay is far better for that, but bad for drainage. However, for a bog type of plant I don't think drainage is an issue so would guess clay is better.
There are some plants that like it wet with moving water so good drainage would be important for them. One species of Utricularia here grows on sandy banks near water level with water constantly on the move. You don't see it in the lowland areas where the water is just standing.
I don't know about "the perfect tropical environment " being here. There's still a lot of challenges. It's just that low temperatures isn't one of them. Have a look at this thread:
