don't imagine that HV distribution wires will have BPL on them. It will be the local 110 V wiring, terminated at residences. So if you see significant amounts of BPL RF noise you are probably pretty close to a residential area. Probably close enough for the locals to be complaining about engine noise.
That wouldn't work, the 440/220/110 system starts and stops at the transformer at my street. BPL has to go across the HV line.