A big part of truck life is managing the limited amount of space you have available to you. Depending on what sort of vehicle you're living in, you may have more or less space available to you, but generally, unless you live in a full on tractor trailer, you're going to have less than 200 ft² of space, so you need to be smart about how and where you keep your belongings. As you can see from the picture above, I was able to increase the overall contiguous space available to me (useful, for example, for a truckwarming party).

Efficiently rearranging your living situation requires a little bit of forethought. For me, the following process worked really well:

1. Make a list. Check it twice, find out who's naughty and who's nice. Just kidding. But you do want to make a list of all the large objects you have in your truck. Generally, this list will include anything stationary (beds, storage, furniture, etc), and anything that takes up a reasonable amount of space, even if it can be moved around pretty easily (like a broom or suitcase, for example). For me, the list included my bed, dresser, and coat rack, as well as a small box of tools.
2. Measure everything. Once you've made your list, measure the length and width of each item on it, and write these dimensions down on your list. Then measure the dimensions of the overall living space. I just looked up the dimensions for the twin bed and the Ikea dresser I built (detailed here), and measured the depth and length of the coat rack (build detailed here). I also looked up the dimensions of the box to confirm my rough measurements.
3. Sketch it out. Now that you know everything you need to place, and the space you have to place it, start figuring out arrangements that make sense. My strategy was to put everything at the back, leaving all of the open space in the front. Since I was trying to maximize the amount of free space I had, I decided to put the bed sideways across the truck, leaving enough room for my box of tools at the foot of the bed. It made sense to move the coat rack there too, because that way, accelerating and braking wouldn't cause my clothes to move all over the place, and it meant I could put in a larger rack. Make sure to take into consideration the extra space you'll need for opening and closing drawers, hanging clothes, and just maneuvering around in general. As for the actual sketching part, you can use a normal piece of graph paper, or make a diagram online, like the one I made and included above.
4. Start shuffling things around. Now that you've planned it out, get to moving! Remove all securements you may have built to keep everything safe, and play your own truck-sized version of Tetris. You might want to make sure it won't be too hot out on the day you plan on moving: hard labor in a hot box is far from the most pleasant of experiences.
5. Secure it back down. As detailed in my previous Tips from the Truck post, you'll want to make sure to properly re-secure everything once you're satisfied with the new arrangement. Maybe take a lap around the block as a trial run before you resume your normal driving.

And voila! Enjoy your new and improved, more spacious, Feng shui living arrangements.