With 5 watts from my FT-817 I was received by these stations:
I didn't use any tuner, the SWR meter on the 817 showed 1 bar or less on all bands. A few metres of the wire was along the ground between the transformer and the fence. I used a Garmin Etrex GPS for timing when to press play on the phone. There was no connection between the radio and car electrics/body, the radio was powered from a separate 3.3Ah SLAB.
The cable between the phone and the microphone connector on the FT-817 had a resistive divider made from a 47K and 2 parallel 2.7K resistors. I also connected capacitors across the input and output of this divider (47nF and 22nF) to remove any RF that might be picked up. With this circuit, the phone volume had to be at half way to give full RF output (with the 817's mic gain at 70). I set the VOX gain to 50, it didn't seem to work any lower than about 50.
View from the top end of the antenna towards the East.