On both the last possible day for the autumnal blot and the winter blot the two stones marks the exact point on the horizon for the sunrise. The distance between the two stones is 3.0m. By coincidence the last possible days for autumnal and winter blot almost exactly occur at the same solar altitude.
The animation shows the sunrice the day before, and exactly on the last possible day of the autumnal blot and the winter blot:
The gradients of the top of the higher stone is in exact alignment with the sun’s path.
The sunrise occurs exactly at the point on the horizon marked by stones exactly on the last possible day for both the winter blot and the autumnal blot. These days are exactly one day before 1 1/2 moon cycle after the autumnal equinox and the winter solstice.
There is no problem in seeing the sunrice. The next dates on which this will occur is February 3th 2015, between 9:15 and 9:40 and November 8th between 8:50 and 9.10.