The Static Vents and Pitots are also located up-front.
So although the front is going up, the wing may not be climbing, and the rear of the plane is actually descending.
Pitots and static ports are up front for a reason - it is an area of the aircraft that is most assured to receive unimpeded (and unmolested) airflow. The location of the probes and ports is specific to the aircraft. While your personal VSI may be interesting to use while driving up and down hills, the IVSI as installed on an aircraft involves tens of thousands of dollars of equipment, and likely well over a hundred thousand dollars worth of engineering and research to get it just right for that aircraft.
The IVSI uses information not only from the static ports, but also has inertial inputs from the IRUs for presenting the most accurate and instantaneous information. While there may be some bouncing about and damping during turbulence, for all other phases of flight, these things are very accurate and fast.