The pitot-static system flight tests I did on flights 8 and 11 also allow the effect of the static source position error on the altitude indication to be determined.

Here is the altitude error, at the test weight. The error is very small at low speed, but does start to increase as the airspeed increases. If the trend continues to higher speeds, the error should still be less than 35 ft at 200 kt.

I will put correction charts in my POH, but given the small errors I will probably not calculate corrections for other weights.