Do these controllers have a way of limiting/controlling max RPM?
With my series system, 67V on the AMD7124 went to 6000+ rpm I got 30+mph on flat roads.
You just might get too much speed.
The Nissan leaf lithium batteries are great and easy for configuring to different voltage and amp hours.
I did not see you saying anything about a BMS. One thing is these batteries will not tolerate any overcharge/over discharge/over current like lead acid batteries.
Abusing these batteries will set them on fire.
Beautiful work otherwise...
To answer one of your questions, yes you can easily parallel modules with shorting bars across each terminal. That is what I did so I have 120Ah pack. Talk with Nick at Hybrid Auto Center and he can set you up with a good Nissan leaf battery pack. I would suggest parallel at least 2 modules (120Ah) if not 3 modules (180Ah) as you are going to be drawing lots of current with 2 controllers. see attachment