Since I had everything set up, I measured again using a triangle waveform instead of sine. Maybe the info will be of value to somebody.
Not too bad. The two meters were almost identical, but were lower than theory would predict for the rectified output, unfiltered. The 4.4 values of both meters look closer to the theoretical VAVG of 4.35 (half of 8.7peak) instead of the theoretical VRMS of 5.02. Maybe I did something wrong. Alas, I don’t have a calibrated precision meter to serve as the ultimate judge.