If, as seems to be the opinion of many of the respondents of this thread (myself included), that the average opponent rating of your opponent can provide some additional insight into the strength of your opponent, then it stands to reason that the average opponent rating of your opponent's opponents also has some relevance.
And if, the average opponent rating of your opponent's opponents can provide some additional insight....
minaton-- you can enter tournaments that have a minimum rating requirement (1900 up, e.g.).
I think the value of playing opponents who are stronger than oneself cannot be overstated. To truly improve at chess or at anything for that matter, it is extremely important to always be surrounded by your betters, so to be continually challenged and inspired to learn from them. Once you attain their level, challenge the next level of better ones! I actually feel my game noticeably suffer when I play too much against weaker opponents and then attempt to face stronger ones again. Sloppy or lazy play and bad habits (that a strong opponent would immediately punish) are reinforced when weaker opponents lets us get away with them.