Our oldest started at 4 months and our youngest started at 6 months.
There's lots of good advice here and I'd agree with everyone saying "go for it!" - one thing to keep in mind, when baby is awake at night, everyone in the camper will be awake. There's no way to sleep when your spouse is taking their turn with the baby, you'll hear everything and feel every movement! (Speaking from experience). I guess I'd just plan to take it real easy the first couple of trips, and don't feel badly for wanting to nap when the baby naps :) (Is there anything better than a nap in the camper??).