Someone in my circles was posting about wanting to buy an E350 van. Price 20 K.
My take: A 350 is too heavy and uses too much gas. Try to find a stripped-down E150 if you can. (They don’t seem to be very easy to find because people like to hang onto them, understandably.) And furnish it your own way with your own DIY lightweight modular furnishings. That’s what I would live in if I wanted to do van life.
Or if you wanted to go more compact; are able to fit your work tools and your life into a more compact footprint, then one of those little Ford Transit Connects. But it looks like even the old used ones are probably pretty expensive.