Anyone with safari experience?

Hi! On the off chance...

Has anyone used the Patagonia Refugio 26L as your bag during a gorilla and/or chimp trek? I own this bag and have so far just used it for local weekend trips. Is it too big for a one day trek in the mountains of Uganda? How does it hold up in the rain? I'll be there in July, which is dry season, but rain is still a possibility. Any other recommendations?

Perhaps I should be asking this in a safari sub, but I thought of y'all first. This sub was invaluable to me when I first started! Convinced me to get the Patagonia Black Hole Mini MLC 30L for my 2+ week trip through Scotland & England last summer and it was perfect.

Thanks in advance for any help!