Queensland Australia.
I never had a licence and I live 10kms ride to any shops with 7 other souls that rely upon me. so these bikes are the backbone to my life.
It doesnt get too cold down up here, cold enough to puts my great coat on and a couple of layers of under garments and a thick scarf. Forget using pedals with all the gear on. Maybe a little pedals to get the blood warm.
Any cold really gets amplified by the wind.
You just need to look at motor cyclist gear, it can be done.
As far as I can tell your original shunt is in the wrong place. I think at least it should go after the 63v cap because the fets are always draining the cap dry with every switching event and it is a small cap too.
all my other controllers negative - input feed go straight to the cap negative terminal then lead to a shunt then to the fets. Not to the shunt, then to the cap, then to the fets.
You can see in this picture the topography between your controller and a MC 36v earlier version. These modifications mayber put inplace to add reliability to the controller under regen. All this gets a little complicated and I need to work out how the changes alter the physics of the circuit.
Certainly that brown cap is very small and would possibly be effected by the switching load of the fet through the shunt into the larger cap and all depends on the smaller brown caps positive feed on the other side too.
On other magic controllers I have seen they use a much larger caps, where on your controller there is only a small cap in their place.