you must have used your bow-thruster a lot! It usually stops after 3 minutes of use (like 18 times 10 seconds).
Making a way to ventilate the bow-thruster will not change much about motor temperature but for sure will bring (more) wet air on the motor and relays, which will lead to ease corrosion on these electric components.
Next time you have more than 25 knots while entering a harbour, try to catch the easiest berth that you see, and come later to a more difficult berth.
The bow-thruster is powerful but cannot do the job in any weather conditions....