If you haven't read all of this thread
there is mention of the South Korean external cooler option. Even if you use your chosen pump, it should be instructive where Toyota engineers place the inlet and outlet.
Given your use case, what you are working toward is a Kinetic Energy Recovery System (KERS). This has implications for sizing the components, less batteries and charger, and more Coulombs passing through the circuits and wires.
You probably know that...