Second what Maoster says. It’s a grim life stuck in a box, so get out of it for a bit.
I’ve got my bedding, clothes, wash stuff etc but that’s all basic stuff. I also have some meals that I can just sling in the microwave or heat up on the stove if I fancy but most of my little places I’ve found to park are near a pub that serves food so I tend to have a meal most nights unless I don’t fancy it. It does help that my unit is well spaced with fridge/freezer, microwave, coffee machine etc etc (no cool box strapped to the front passenger seat here!)
Oh don’t forget entertainment whether that be films on a tablet, books or multiple copies of Razzle or some other genetlemens publication. If the latter also take a toffee hammer so you can smash your bedding back into a comfortable shape after it’s toughened up.