Took my 6yo camping for the first time - massive failure

So we went to Shenandoah last weekend with my oldest (6) and youngest (3). Thought it'd be great bonding time. Six hours in, 6yo is screaming that the sleeping bag is "too squeezy" and refuses to sleep. Then 3yo gets sick from eating too many trail mix peanuts. We ended up leaving at 2am and driving home. Wife isn't speaking to me lol. Anyone else have a first camping trip that went sideways? How do you know when kids are actually ready for overnight camping?