A real time spectrum analyzer (the data recording/FFT type) is the right tool for capturing peak EMI levels from low frequency events (diode noise). Alas, these run over $8K plus a few thousand for ancillary gear. I do have the old Spectrum Probes from Smith Designs.
The "meter" you found is a ''toy'' broad spectrum meter, which would not detect anything from my equipment. The specifications are a farce- they mention power but then don't give power units, instead millivolts but not in units with any meaning like mv/m2.
Cornet, GHz Solutions, and Acousticom all make fairly decent, semi-calibrated broadband meters. I have an old Aaronia and a Cornet broadband meter, but they are not sensitive enough or shielded properly for conducted EMI measurment; they would only see the highest ambient radio/microwave level across their entire range of frequencies. They are useful tools, but not for this job.
For diode type noise (pulsed broad spectrum at ELF rate) the well chosen AM radio is actually the far more sensitive tool.
I did get a little work done yesterday. All is well, i found the Franklin well pump QD controller diode (Triac actually) noise is fairly well controlled with a single common mode choke. I'm considering some wiring changes for light filtering of power for the use of the well pump and future air compressor motor, with more substantial filtering of the AC distributed to the shop, since that shares the conduit with my 120 VDC line.
I've got to address the needed changes to my PV charge controller now; there is still some interaction and minor oscillation at high PV/low inverter load. The inverter load (3 mv of ripple for the well pump) is also affecting the float state circuitry- it gets kicked out to bulk charge when the inverter is running and it should stay in float.
This afternoon I should get the copper flashing to extend the HF ground over to the battery bank earth ground connection.