Low speed, high torque. Need some component help.

I’ve got a project in mind, it's going to be a delta style (2 wheels in back) 3 wheeler, one wheel drive to help with turning. This will be for low speed (less than 15 mph, usually walking speed) but it needs to have plenty of torque to move around 400-425 lbs (vehicle, rider, and gear) through grass and hopefully up some small hills, minimum usable range is 5 miles and 50-60 stops and starts. I’m thinking I’ll do 10s (maybe 12s) lipo. Tires will be 10" and will have room for a jackshaft if needed, but would prefer not to. That's all I've really got so far, because the more I read the more I question all my other choices.

• I was thinking 2000w sensored scooter motor (from electricscooterparts.com) I was thinking the larger size, as compared to common hobby outrunners, would mean bigger stator and thus more torque.
• This started off being more skateboard than scooter, so was looking at their forums and thought the vesc seemed like it would be the way to go. I really like the ability to get telemetry from the vesc, and saw the Power VeloCity one also has that; Other than those, I'm really not sure what else is out there and would be the best option. I tried some searching, but seems like so many other sites I've shopped at are rebranding the same controllers as their own.

Thanks in advance.