The best bike for that kind of work is going to be one of the mid drive ones...
It doesn't sound as if the OP is too hands-on, but for my money, I'd learn from those members here already hauling cargo and do a build; that seems to offer the best bang for your buck being tailored to best suit the purpose you're going to put the bike to.
Current discussions IIRC include
@guerney using a Dahon with BBS01 mid-drive to haul pumpkins in a trailer, and
@Nealh building his mid-powered TSDZ2 Kona to (presumably) haul Bee-Juice?
It seems to me that the trouble with most off-the-shelf e-cargo bikes is they're built to offer wide appeal to suit a multitude of uses, so by definition you end up with a compromise. How much better to balance the weight you need to carry, the type of cargo you need to carry, the terrain you need to cover, the torque/speed/gearing you're going to need, and the budget you have to spend? A second-hand frame and a mid-drive kit will likely offer a cheaper overall solution to give the OP an e-cargo bike that's much better suited to what they specifically want to do with it... and that probably does mean mid-drive.
With the expert guidance available on this (and other) forums it seems anything is possible, even for those who don't yet know one end of a battery from the other.