2m FT8 QRP (Saturday)

In a short while I hope to go on 2m FT8 with 2.5W and the big-wheel omni. Yesterday I had 1 QSO, but was widely spotted despite my low ERP signal. 

Although the conventional wisdom is this is due to aircraft reflection, I am still puzzled: these DX spots seem to occur at almost any time, so I am wondering if FT8 is allowing QRP stations to access some scatter modes that would not be possible with CW or SSB at these ERPs?

I expect my 2m FT8 reports are a mix of tropo, aircraft and other scatter, possibly with some random MS. Not quite sure how long an MS burst has to get a successful FT8 decode. I suspect far less than the 15 seconds a TX FT8 burst lasts.

My ERP is probably less than 5W.  The big-wheel has a little horizontal gain, but the coax has some loss.

UPDATE 1034z:  My 2m FT8 QRP was turned on at 0955z. So far, 10 spots of my QRP TX including (again) EI2FG (565km) and 5 spots on RX.

UPDATE 1105z: 13 stations have so far spotted my QRP 2m FT8 TX.

UPDATE 1508z:  16 spots of my 2m FT8 QRP TX today including EI and GI as the map shows.

UPDATE 1931z: 18 stations have spotted my 2m FT8 QRP TX today.