We have an existing barb wire fence on the south end of our property that in well inside our property line. We want to install a new fence on the actual property line. We need to keep barb wire because occasionally cattle break through another fence into that area, and we want to keep them out. We're total newbies at this. We originally thought we would install 4 strands, but we're wondering if 3 strands would be enough. Also, we're considering 6 1/2' T-posts, and installing them 18-24 inches in the ground. Is that enough? I would appreciate anyone's thoughts. We'd like to do this as inexpensively as possible right now.