K.E.
We're taking our 21 month old camping next week for the first time, and at the advice of another mamasource mom, we spent the last two nights in a tent in our backyard. I thought he would adjust great since he's always fallen asleep really quickly at night, but the first night he totally freaked out and was up until 11:30! The second night he did much better. It will be different with a younger child, but there are so many different noises when sleeping out in a tent, that it might be worth doing a couple of trial runs before you go.
Definitely find an all natural bug spray; we just bought one (Deet-free!) at Longs, made with lemongrass and citronella and some herbs and things, which I'll feel much better about putting on his skin!
You probably won't need to worry about him getting bored; with so many new things to see, and lots of family to hold him, you might need to worry more about him getting over-stimulated!
Also, don't worry too much about getting dirty... As my husband said, we can get clean when we get home!