Long pants maybe, hiking boots, no. I have 1 pair of really good Northface pants that are summer weight--I look like a nerd in them, but i think it is a guy thing; we like gear with pockets, zippers, and velcro.
An old pair of Khakis would be great, though. Not blue jeans as they don't "breath" at all.
Not big hiking boots as they take up so much room and you seldom wear them. Try an old pair of sneakers [with a little tread], then just leave them there.
Tell Marti & Eldon & Pedro that Big Frank says hello. We were there last month! I took the Num Li Punit & Blue Creek cave trip. I really enjoyed the ruins and cave float, although it was A LOT of windshield time, so I only give a reserved recommendation.
If you want to know anything else, just post for me:-]