You could maybe do a custom metal tube lines in place of the radiator hoses (I used to have pics of a setup on a straight-6 67 C10 that had this) with rubber joints for the bends and where it connected to the radiator and engine. Then grab some exhaust wrap and wrap the inlets and outlets from the radiator and engine... Possibly wrap the side tanks on the radiator too. All the cooling action happens in the fins so it shouldn't effect cooling. Maybe have a display reading trans temp since it's cooler is typically inside the radiator tanks on a typical car.
Not sure if that's totally what your looking for, but that's about as much as I'd want to insulate the cooling system on the car.
The reservoir's main goal is to collect coolant that flows out as the engine heats up (typically in an over heating situation) and the coolant expands in volume. Older cars used to just dump it on the ground via a rubber line that ran down under the car.
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Two examples of metal ratiator lines:
Straight metal pipes
Universal metal bendy hoses