So are there any tips, short of going to an alternate location, to try for international DX with my PL-380 and Select-A-Tenna? I live in a fairly RF-saturated environment, which doesn't help, and it's difficult, if not impossible, for me to travel to other locations at this time. (If I had the opportunity, I might want to try going to somewhere west of Santa Barbara, CA (on the California coast) to try for some DX, but that doesn't look like it will happen anytime in the near future.) For now, though, the maximum extent of my "DXpedition trek" would extend to my back yard on the 1/2-acre lot.
And, for "international", for purposes of this post, I'm not including Mexico - I can get several AM and FM stations 24/7, some of which peg the SNR meter, and one AM pegs the RSSI meter in the daytime as well.

Or, should I resign myself to never doing any meaningful DX from here, and sell my PL-380? I do remember Scott Willingham in a post last week or so mentioning something about 3 ways to improve selectivity, one of which was to install passive filtering in front of the DSP chip. Is doing something like that that even remotely a possibility? And, while I'm at it (if I was to attempt something like that), what about pulling the guts out of the PL-380 cabinet, substituting a separate loopstick (would have to be no longer than 3 to 4 inches long and 1/2 inch thick, assuming it takes the entire width and almost the entire thickness of the radio, as it will have to fit in my pants pocket and 4" is the absolute maximum width that would reasonably go in there - my PL-380 will go in there but it's awkward), and basically crafting my own vertically-oriented ultralight based on the PL-380's guts, or would it not even be considered in the "unlimited" category? :(