Your term "cost effective" is probably the key term in this conversation. Chances are (depending on a great many variables, of course), that your B190 is only worth a few thousand if you wanted to try selling it. You could easily spend a few thousand to have someone do the kind of mods you describe. There was a song I recall (Thousand Dollar Car?) that stated it rather poetically, something to the effect of "take a thousand-dollar-car, put another thousand into it to make it useable, and what you have is a two thousand dollar thousand-dollar-car."
No matter what you do, you can't think of it as an investment, and you will never get your money back. If that isn't a problem, then I am sure you can find someone who will do the work. There is an ever growing "van-life" movement out there where DIYers and professionals alike are modding vans to be lived in. Heck, the guys who mod vans to make them handicap accessible may be able to help you as well.