Prefab & Practice. Build components and assemblies in your apt, before you buy a bus.
Build a composting toilet ealrly on. You may need one on the drive home & the first demo day. It may take time to cultivate a relationship between your ass & the bucket life.
You can prefab a working vanity sink with a water reservoir, foot pump and drain bucket.
A solar water heater makes enough heat to wash your parts daily. You can set up a basin outside your bus. Better to be experienced with it, beforehand.
Practice cooking with only a grill & one small appliance. Non-perishable foods, as cooler refridgeration is limited & unreliable.
Can you buy & build out a small trailer first? To house tools, materials and a central energy production center? (Gene, batteries, 1-3 solar panels)
Otherwise, an onsite shipping container, shed or at least a large tent. Maybe some sleeping in there, too.
Do you have experience living in the wild? Military, homelessness, long term sailing, nomadic hunting....