I did it at 8 months, it was fine. The things that bugged me most were -
Lots of bending down, picking stuff up - as camping is v ground based I really noticed how everything is on the floor so I would advise to try to keep whatever you can at waist level - get a long table to put food and other stuff on. Really this would be my top tip. I didn't suffer with pregnancy back pain until I went camping!
Even with a 10cm self inflating mat my hips hurt from lying on my side at night. A lilo on top might have been better/squashier. Take LOTS of pillows.
Heart burn (if you get it) was made loads worse by all the bending down and eating extremely calorific food nutritious camping cooking so don't forget GAVISCON, it was my best friend.
My legs got cramps more - perhaps cos they were colder? Wrap up.
Strict instructions to other DC's to pick toys up, I was often nearly tripping over them as I got fed up of bending over picking things up - leave a big bucket out for them to chuck them all in.
Depending on age of other DC's - if they need help tying laces/straps etc just give them wellies they can put on and off themselves. They are in and out tent all day and you really don't want to be bending over doing shoes every 10 mins.
Bucket with lid to wee in.
Decent moon chair that is yours and only yours to sit in.
Oh and can I say that camping with a newborn is easy, very easy if they are not criers, obviously if they have colic or similar its different, but don't write it off if you really want to go - see how your baby is. We took DS camping at 6 weeks, he was very portable, slept lots, only cried occasionally and was just an extension of me really. It was fun.