I tow a Conway cruiser with a 1.4 civic with no problems. Its max laden weight is 750kg,The four berth campers are around the same weight, unless it is a very recent countryman (the one with the toilet) its a little heavier.
You need to check your towing weights first, some family cars like the zafira or c max don't have good towing weight for the size of the car and once fc on the back dose not leave you much for anything else unless you go for a diesel. We had a 1.6 scenic it was gutless.
Check your rig here
For the towed vehicle, scroll down and add trailer ... then select the top one on the next page ... then you will be able to adjust all weights etc to fit your FC on the next page.
Kelper - thanks for the link. Being brand new to the TT and towing its very useful (and reassuring) to know that when we put our details in it gave us the big thumbs up!!