Absolutely no levis IMO, iThey can get wet just from sweat they will be heavy, uncomfortable, and chafe them horribly.
Scouts usually travel to/from where they are going in Class A uniform. The official boy scout pants are nylon zip offs. Most troops allow them to wear any pants as long as some shade of green (because official is $50, but this is where they need the right ones.
Cotton underwear too, synthetic compression shorts at walmart are 8.99 dont need spare IMO.
Most boys do not change clothes or underwear on any camping trips, even "car camping".
need synthetic socks too, not cotton or they can get blisters badly. The official bsa socks that are part of the uniform are acrylic and will do.