Saraah,
what is your car and have you looked on https://towcar.info/
Most UK supplied 430's from about 2000 onwards will have a 1200kg axle/max load. If you see 5 wheel studs/bolts it is 1200kg, 4 means 1000kg. They offer a double berth at the back and single at the front. In the middle is a small loo suitable for night-time use opposite the kitchen. This would be my choice, and not because we have one, but because it meets your requirements.
The 85% limit is a guide for new towers, but Eribas are not your average van. They are lower, streamlined and far more stable than your traditional wobbly white box. You need to look in your car handbook for the weights allowed. The information is probably also on the B pillar drivers side. The weights could be higher, or possibly lower than the 85% depending upon manufacturer. Renault are often lower.
Colin