I am halfway around my yard installing my fence and all was well up until now. In one corner of my yard is a slope going down. From where my last post in ground is, to the corner of lot is 24'. It is about 4' of slope from the bottom of last section installed to the corner; and then I will have to go up on the next side. Is there any way to do this fence, other than stepping it down, or filling in that spot? If I fill it, do I use railroad ties to keep in the fill? Please help. Thanks.