The caravan organisations do recommend an 85% ratio (between the car's unladen weight and the 'van's MTPLM*) for safety reasons. If you are experienced you can tow up to 100% or to whatever the car manufacturer states as a max, in SteveC's case not a lot. Renaults are famous for low towing figures. It's not the weight of the car it's whatever the manufacturer states as a towing limit.
If you exceed the 3.5 tonnes train weight then you can get into licencing issues if you are of the younger type. Doesn't affect me!!!
Eribas are lovely things to tow, being light and narrow and with the pop top the frontal area is low, the compromise is interior space. Our 3 berth Triton isn't really suitable for three. Even with two you cannot really both be standing at the same time!
Bascamp comes as a 4 berth as well, it is longer, wider and much taller than a Triton but its MTPLM* is about the same, just shy of 1200kg.
A shower would be nice but we make do with a night time visit only toilet and a kettle. We think that a cooker is completely unneccessary for camping. It's supposed to be a holiday for all.
* Maximum Technically Permissible Laden Mass