The subject of this thread caught my eye so I figured I'd chime in.
I think--depending on where you live and plan to ride this--that you should consider building something like a real, full-size surrey:
I've long thought that this type of vehicle would be a better fit as a low-speed pedal-electric for people who live out in the country than the ones that have been marketed so far. This way, Instead of huddling to the side of the road, you could take over a full lane like an Amish carriage and have great visibility and even (maybe) a better margin of safety due to your greater elevation than the bulk of the average motor vehicle's heaviest parts. Also, those huge wheels would have a smoother ride and be able to roll over pretty much anything!
As more justification, Jay Leno has an antique electric car that is sort of this vehicle type, and he claims that it's a joy to drive because he's up so high! Yes, I realize the aerodynamics would be a challenge.