Of course there is very limited storage space on the truck. It's like a tiny house but even smaller! So you have to get smart about it. I'm in no way an expert on this as our truck still looks like a mess too but there are a few things that work for me and maybe it will help you.
So first: refrigerator space! If you're lucky enough to be able to have a dorm sized fridge on your truck and it doesn't break on you in a short time, then kudos to you! We have one of the Dometic fridges that are specifically made for trucks/RVs as they're build to withstand all the bumps and vibrations which regular fridges are not. So yes they are expensive but worth it after you've had a few regular fridges break after a few months.
But as the space is more limited, how can you store stuff for meals for 5-6 days? It does take some creative skills!
I always have Ziploc bags on board because as soon as we get our groceries, I repack half of them. They are either packaged in too bulky cartons/containers or in case of bags they're too blown up etc.
So what do I do? First I plan my meals ahead for 5-6 days and think of what ingredients I'd need for each meal. I try to come up with things like for example chicken noodle soup; what does that need? Chicken obviously, so I get two half chickens, put them in the Instant Pot (electric pressure cooker) and when done put them in a bowl or plate to let the, cool off. Pull the chicken meat off both halves. One half goes into the soup, the other half goes into a Ziploc bag to make e.g. chicken salad with. The soup will also need celery, carrots and onions. I know I will not need the amount of all 3 just for soup. So I use half and with the other half I can make for instance beef stew.
So then all I'd need is beef stew meat. Now you pretty much have 4 meals and probably leftovers as well. These are just examples but if you think about it, you can create a lot of meals with similar ingredients without making the same over and over.
We also have a 3-drawer storage thing that fits into one of the cubbyholes of our truck. The top drawer has all kinds of loose stuff in it.
The second drawer I put the spices in I always use and the third is for the cooking utensils. So they're right next to the little pull out drawer table and easy to use/easy access.
Hopefully this helps at least one of you out there! Safe travels!