There's a few companies making e cargo bikes. I've had a go on a tern, and it was.quite good with a few options.
https://www.ternbicycles.com/uk/bikes/gsd
If you learn how to manage the power use it makes a huge difference. In full power I get around 35 miles. If I use the power only when I really need it, I've managed over 100 miles. The power cuts off on my bike at 15.6 MPH, because I'm cycling fit I can keep the speed, on average, between 18 and 20 mph, so even with the power switched on, nothing is used. I have three settings (low/medium/high) but leave it in low most of the time, and only use high when I really need it. The Tern bikes at the time I had a demo, had different battery size options, plus the ability to carry a spare. Personally I think these bikes are becoming too over (electronically) complicated, and as much as I like mine, I don't think they offer value for money. For anyone thinking of towing a trailer avoid front wheel drive bikes, as these can "wheel spin" in the wet when climbing hills.