I wish I was in a market where used was an option... That would be a good route to take, but I have yet to see a box bike on the road or in a shop in Pittsburgh.
I had a look at Madsen's website last night. It's not a front loader, but it seems to be functionally equivalent. Huge payload, rides like a bike and comes with a rain canopy, and you can get one loaded with a mid drive motor, shipped, for $4500. That one is on my list now.
Regardless, this is kind of a pipe dream at this point. I have lots of hurdles to clear, both financial and familial, before that will become a reality. One thing I'm thinking about as an intermediate step is to just get a Bafang kit for my old hybrid bike and either an xtracycle kit or a trailer to prove the utility of such a vehicle before I go whole hog on a made-to-order utility bike. My wife likes that I commute by bike, but anytime I bring up the possibility of a bike as car replacement, it is not received well. We'll see what happens.