Wow that’s a lot of assuming and supposing :) no shop right? no tools right? a place to work and tools for under 3K right? . This ones easy buy a pocket knife, set in your living room and whittle . So far you have $20 spent for a pocket knife. You might need another $200 for a decent vacuum to clean up all the shavings you made in your living room.
We love natural light as much as anyone, and the big windows in our van were something we were super excited about. But when you're living in a van, you'll want some privacy. Trust me. You'll also need curtains to keep out the lights when you're trying to sleep. Making your own curtains can seem like a daunting task, but it's not all that hard. (I speak as someone who had to look up a tutorial to operate a sewing machine!)