OP chose a hill 250 meters above sea level, and also has an antenna about 5m high. According to a calculator I found[1] that puts the distance of the horizon at

OP chose a hill 250 meters above sea level, and also has an antenna about 5m high. According to a calculator I found[1] that puts the distance of the horizon at roughly 57km. So plenty of range to still be in LOS of the transmitter. [1] https://www.omnicalculator.com/physics/earth-curvature https://www.omnicalculator.com/physics/earth-curvature