That directionality about 'off the sides' of a dipole apply to horizontally mounted dipoles. A vertically mounted dipole isn't going to be very directional at all. Unfortunately, the majority of signal polarizations is vertical, not horizontal. After a signal makes one 'skip' then it's polarity changes. Opposite polarity signals don't 'hear' each other too well at less than 'skip' distances. That means that locally, if your antenna is horizontal and their antenna is vertically polarized, signals are going to be weak to/from each other. That's a very 'rough' way of saying it, and there are exceptioons, but generally that's about how it works out.
Don't misunderstand, a dipole will certainly be better than nothing, so do it. If you can figure a way of changing it from a horizontal mounting to a vertical mounting (hang the thing from one end), you will definitely hear a difference.
Have fun.
- 'Doc