I am a beginner please be nice

So basically I want to buy an cheap old diesel tractor and rebuild it to an EV or EA Electric Agricultural, lol.
I need some experienced advice and recommendations/opinions. So here are my questions and concerns
The main objective is to have a lot of torque at low speed < 1km/h or less because for some planting applications our current Massy Fergusson is to fast even at the lowest speed. EV would be good because its silent give a lot of torque even at lower RPM, we could use our solar overproduction for the tractor and generally less maintenance compared to old diesel and I feel that the battery technologies are good enough now.
Q1. What are good easily hackable EV small (+/- 10 to 30 Kw is fine) motors with a lot of torque at roughly 1000 to 1700 rpm, I think I would need a reduction gear to reduce car EV motor to high torque low speed. I want low tech as possible if possible low voltage around 72V to 220V.
(available in garages or Ebay in EU)
Q2. Generally hackable controller/BMS so that pretty much every aspect is readable or controllable somehow. Mainly because I want to integrate it with a opensource GPS system called AGopenGPS for automatic GPS steering.
Q3. I want to avoid proprietary locked down software because I want to do this to save money all in aiming for +/- 2 to 5k euro. Or less

my background: I have high school degree on electronics with very basic mechanical knowledge and currently studying for my bachelors in Electronics and IT.
any opinions or recommendations welcome.