Your over thinking it. There’s loads of room for 5 Have a think about what you would be taking if you were going camping in a car, then cross off what you’ve already got Built in - water, gas bottle, table, beds for 4, 2 chairs. You’ve then got cupboards for food, wardrobe space, overhead lockers, rear cupboard, under seat draw etc etc. Just be sensible with your selection of awning & don’t get one that fills the boot.
Don’t worry about storms etc - think positive ie it’s better than just having a tent. At least you’ve got somewhere you could all squeeze inside and make a cuppa if you had to.
We’ve done 6 up in summer in France in a Cali SE with 2 extra seats & it was fine.
Also done 3 up in Cornwall in the rain & it was awfull
It really depends on every bodies attitude - if everyone wants it to work it will.
