Don't feel too bad about your WYFR-1557's reception barely missing the all-time stock Ultralight distance record.
Right after my post to you, Kevin Schanilec sent me a post claiming the stock Ultralight distance record himself, for his stock E100 logging of 3LO-774 (in Melbourne, Australia) from Seward, Alaska. The bizarre thing is that I heard traces of this 3LO-774 station myself during a July trip to Grayland, WA on a stock SRF-T615 (which is a slightly greater distance), but didn't think the reception was substantial enough for a formal logging (it was solid copy on a modified E100, but only had traces on the stock SRF-T615). So Kevin's 3LO-774 logging (7,684 miles, or 12,373 km) should indeed be considered the current record, in my opinion-- at least until somebody using a stock ULR at Grayland has a more substantial logging of 3LO, or some other station in Australia.
It certainly seems that Ultralight DXing records were made to be broken :>)