Happy fox hunting as its called. The trick will be operating down in the 80m region, where conventional antennas are too big and bulky up use for direction finding.
A quick search of the topic, e.g. "80m ARDF" shows that there are some kits and radios, including Chinese ones, that can be used for direction finding at these frequencies. Basically, it looks like they wrapped a coil of antenna around a ferrite core to get it to operate at these frequencies and provide a directional null.
The good news is that if you can find the source, the FCC is in your side in terms of eliminating the interference, but it's recommended to try the courteous approach before engaging them.