I will be doing a gorilla trek in early April in Bwindi. The tour company recommends a rain jacket/poncho, long sleeve shirt, long pants, etc. which I am familiar with having done a chimp trek last year. They also recommend a sweater or fleece for the evenings as the mountains areas are chilly. My question is whether I would need a sweater or something warmer on the trek? Just curious about how much layering I should plan on.