Bucket or washing up bowl. Can be used to carry dirty items to and from the washing up area. For washing hands/feet before going into the tent (I have muddy children!), with cold water for cooling beer or prosecco and just being handy.
Supermarket or shop re-usable bags (about £1 each ones). Some people use these for clothes (we don't) but can also be used to take items to the wash block - ie. wash bags, towels and jammies for all children which saves them being dropped or lost. Bag filled with items for a day out or picnic lunch. Our best idea is to use it as a shoe rack. We just put our shoes/flip-flops in it when going into the tent to save on dirt and mud in the tent.
Surely … all items of equipment you have bought or want to buy are "essential" otherwise you would not have bought it in the first place or looking to buy it?
…. now there must be some reasonable explanation for those that have a tent for everyday of the week.
Been there and done that. Started with a basic set up, bought more and more then added a trailer. Worked up to a folding camper. Now the kids are grown up and we have downsized again and I am absolutely determined that we are sticking with what we have.
That said I want to be comfortable so good sleeping bags and camp beds are essential. Think about a basic cooking kit, a table of some kind, something to sit on and lights. You probably need a washing up bowl and having a coolbox saves you running to the shop all the time. A fleece blanket each is good for wrapping around you on chilly evenings, and can be used as a picnic blanket. Folding canvas storage boxes are great and take up little space in the car.
I stay away from camping shops and online camping sites now or I will buy things we really dont need!