It was where we stored all our lumber, tools, silicone, caulk, nails, screws, etc. Look at all the space for storing our construction equipment.
Some people say that building out a skoolie is about making space compromises for what's important. A comfy bed that fits us both (plus Korra for snuggles in the winter) was a non-negotiable.
Having lived in a minivan for a summer, we knew we wanted a queen sized mattress and enough room to sit up properly in the bed.