Try first printing the negative and 'burning' in the sky. By that I mean holding something over the remainder of the negative about 6" above and giving the sky extra exposure. It is quite a simple technique and to get the best out of a negative I have to do it most of the time. If the horizon is uneven, i.e. not a straight line mark out the horizon on a piece of paper and cut around the mark and hold this over the section where you don't want to increase the exposure. The line you mark out should be about half size of the intended print to allow for the card not to block everything out when it is above the image when being printed.. It doesn't have to be exact, a little unevenness will help to avoid a marked line. Make sure you move the card around during this extra exposure to avoid this hard line.

The times I have tried Farmers Reducer on a negative (Very few) I have always finished up with a more grainy negative and you will have plenty of that anyway, and if you over do the Farmers there is no going back and the negative is more or less toast.