Maybe I'm going mad here but....
What is wrong with a standard 2 wheel bike with a few pouches, with some kind of electric power involved. Easy to repair, easy to put in the back of a van if it needs moving or breaks down, easy to cycle through traffic, on pavement etc.
Then design a slim 3 wheel trailer that can hook onto the back of the bike. The trailer can be unhooked and part of it doubles up as a HCT. That way, if you have flats or areas that it's easier to push a HCT around, you lock your bike up and push part of the trailer round. And vice versa, if you have a few farms or houses with long drives, you lock the trailer up and cycle there.
The trailer can be loaded up inside the office so you're not prepping your round, tying up, then pushing it out on a York etc, having to bring the York back in which wastes time. You just prep and pack the trolley, then push it out, clip it to a bike and off you go.
We don't look like idiots, there's plenty flexibility so we aren't tied to one delivery method (cycling or trolley), can be loaded up quicker indoors, and overall there's less risk compared to going out on silly trikes with irate drivers behind you making dangerous manoeuvres to get past.
The day is gonna come when we’re all gonna have to testify.
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