I 2nd the "pleather" vote. Real leather will just not be practical with the moisture. My former trailer was a Boler
and in the morning there always was 'dew' all over the inside on the ensolite, moisture is going to happen, no way around that.
But good news, there are some wonderful products out now.
J. Ennis Fabrics has two nice products. Ultraleather is a great feeling fabric at a lower price. The high end Brisa product line is actually breathable leather look - most people would be hard pressed to tell it wasn't leather. I think a breathable fabric to sleep on is important, otherwise you will be too hot and uncomfortable. I think this product is available on both sides of the border.
ETA: I see you are in Moncton. J.Ennis has locations in Toronto & Montreal, so your local upholstry shop should be able to show you samples and bring those products in for you.