Exactly Pauline and you haven't got unlimited space - you can't tuck odd things into a corner left spare from the big things like you can with a car boot, or the inside of a car. Went on hols en famille one time, 10 of us 3 of them kids. We had the Xantia and a trailer, No 1 daughter had SIL's Disco, two GCs in the back and a trailer, SIL's bro had a car with him, his g/f, their 2yo son, and their joint friend Neil. All the fishing equipment 4 tents, a bivvy, a gazebo, a freestanding stove & camping gaz bottles.plus 2 Coleman petrol stoves, two ditto lamps, coolboxes, two picnic tables (the fold-up 4 seater ones) sundry chairs, buckets, bedchairs, sleeping bags - you name it - we had it.
Several essentials eg Duct tape, the gas spanner, some pegs, spare guy rope, and I dunno what else, were stowed under the Xantia driving seat. Sometime during the second week one of the kids had lost something, as they do. So Tim being the eldest at about 7, was directed to supervise the hunt for whatever. Anyway they couldn't find it whatever it was. His Dad cross examined him - Well where have you looked? And Tim replied that they had looked everywhere - honest Dad. We even looked behind Grandad's seat in his car!
We howled with laughter. We'd known all along exactly where Liam's teddy that he wouldn't ever go to bed without, was. His mother had accidentally dropped it in the lake that morning when her hands were too full clearing up after him so he'd been in the wash and been hanging on the line to dry at the back of the lake owner's house in the sun, since then!