Generally, the VESC is best if you use 10-12S. A very well proven and common setup is 10S with a 190kV motor. Since you’re using a single motor and have a few hills, the bigger the motor the better. I’d go with a 6374 190kV motor if you can find one since its pretty much the biggest motor you’ll be able to get and it’s the right kV. Those changes would give you significantly more power and cooler performance.
That would give you a top speed of roughly 40km/h. If you don’t need this much speed then I’d consider going with a 13T motor pulley cause it would give you better hill climbing with a little lower top speed. Since pulleys are so cheap I’d get the 16T and 13T and see which one you like most.
Also, drop through decks aren’t the best idea since you’ll need as much clearance as you can get for the motor and enclosure. You can get cheap blank decks here if you’re on a budget.
For a single drive running 6s look at DIY’s 260kv 6354 motor,. One of my builds is using this motor and x2 8000mah 3s Zippy lipos. It’s no speed demon, but it does a good job. I get about 11 miles and 18mph.
My build log is in this thread, shows all the parts and the math behind the values.
The setup is good. Just don’t forget the small stuff. The VESC motor wires are 5.5mm bullets while the SK3 motor wires are 4mm bullets. So get the connectors you need and find/get a soldering station to change them.
I (at 170lbs) ran a single drive 6364 190kv 9s for 6 months in college. Was perfectly fine with it. Make sure to purchase protection gear as well (at least a helmet). Get loctite (Home Depot/Amazon).