Will this work properly?

I would instead run low kv motor (149/170/190kv) on 10s - it avoids the 60k ERPM issue w/ VESC, and then you adjust the gearing 15/36 or 15/40 to keep speeds reasonable. It will climb hills better, and accelerate better than a taller geared setup.

I realised it was going to cost more than expected so I cut down the batteries to 2 4s instead, but it should still be fine right? the top speed is ca. 30 kph which is more than enough