Over the years I developed a kit that was just right for me but it went through many reincarnations till I got it right. Basically you want a kit that will split in two, one part that stays in the cab and the rest you take home and wash/clean/replace ( assuming you have the same wagon that is.)
Mine used to consist of
Good basic washing gear inc apart from the obvious, loads of flannels for cab washes when stuck, wet wipes and I used one of those wet electric razers which only needed a charge every two weeks. mirror, Washing up bowl to store it all in and take a couple of towels so one can dry while you use the other. One of those 5 litre mineral water bottles from tescos
Laptop for entertainment and routfinding. I used to get the missus to tape dvds in the week of stuff I liked or get the free dvds with sunday papers. Saves driving yourself mad with crap tv reception when surrounded by metal in truckparks and you can watch what you enjoy
hard rations for emergencies, I used those rice sachets and stew or curry in tins. Tinned fruit, sticky milk, suger cubes,( Granulated gets everywhere)
Instant tea, biscuits, things like that. You can always have a brew and a bite anytime. I used to take two or three fresh meals a week the missus cooked like cottage pie in foil tins and warrm up in mobile oven (24v) I used to eat out once normally. Proper pots and mugs as I hate plastic and tin, makes you feel you are in the scouts. You can feel a bit civilised!! small pan, small frying pan all non stick
Sleeping bags I hated, always made me feel confined. Good double duvet and a fleece blanket so you could lie on it in hot weather or stick your legs out the side. Double duvet meant you could lie on one half and cover with other.
(maybe just me but found it softer and more flexible) Good pillow makes all the difference and you can wash the duvet and pillow cover without luggging it all home.
If your tipping a good tip is to take a waterproof bag you can put your mucky boots and other items in and leave on the catwalk overnight as they tend to stink the cab up with nightheaters on. (I used to do farm deliveries and theres nothing like sleeping with the great smell of [zb] Youy can also put your dirty washing in as you take it off as this tends to get a bit manky by thursday.
Small fridge (big ones get so much in the way) and 24v only as droppers are a pain.
Finally a good selection of books, Personally I used to restrict my tv/dvd as I used to find I,d lie there boggling at it till late cos I was tooo idle to switch it off
I read and always nodded off that way. I was totally paranoid about battery levels and always ran the engine for 1/2 hour after tv fridge etc. never travelled woithout jump leads ever in case I screwed up and needed a jump start
Its all personal choice of course but you may get an idea from that that will make your life easier. I used to hate lugging shedfulls home everyweekend so trimmed everthing to smallest levels and sizes