Now that you have a 2D layout of your van, and know what you need and don't need, it's time for us to 3D pan your layout.
This is where things start to get detailed with real world measurements.
There are a few different software's that will help you 3D design your van:
VanSpace3D (recommended)
VanSpace3D is created specifically to design floor plans for vans and buses. Plus, it includes hundreds of pre-built components and design elements that are customizable. So most of the hard work is done for you!
It's a great software for beginners with less of a learning curve then the others. Here's a step-by-step tutorial on how to use VanSpace3D
Sketchup
SketchUp is a 3D modeling software that allows users to create and manipulate 3D models of buildings, landscapes, furniture, and other objects. It is commonly used in architecture and interior design.
Since this tool is designed for a broad range of use cases (and not specific to vanlife) it is a little bit harder to use as compared to VanSpace3D
That begin said, it is very possible to 3D design your van using Sketchup and it is one of the more popular options.