Ooh, peppermint is really great for cooling. I also think that peppermint supposedly repels spiders, whereas rosemary might not — so that's certainly an advantage!

I love ziplocs for liquid items. If you want to try a featherlight packing cube, I've been using (and LOVE) this one by MUJI:

https://www.muji.us/collections/garment-organization-case/products/gusset-case-f9s8

Or this double-layered one:

https://www.muji.us/collections/garment-organization-case/products/double-layer-gusset-case-f9s8

(I forget which size I have though!)