Trace, often there is no way to start 'massive opposition' to anything. The man you saw was alone; I am sure there have been times when you have felt alone in your convictions as well.
Why not join him? Why not find a suitable public place where you would be able to pass out literature, wear a sign, pray the Rosary?
Where do you live, by the way? There is a clinic not far from me where a solitary man is often seen wearing a sign and/or carrying a Crucifix. I am on the East Coast.
Remember, too, that above ALL else, the most important consideration in protesting these things is that we LIVE SANCTIFIED LIVES; a life that is lived in sin and devoid of grace can have all the moral convictions it wants and still have no power from Heaven.
PRAY Our Lady's Rosary daily. OFFER your sadness and frustration and anger at the horror of the baby-butchering to Our Lord as a reparation for the offenses against His love, mercy, holiness and untold graces. Make good confession often and stay well-read in Scripture, the teachings of the Church and the lives of the saints.
These, and not facts and figures, are the weapons of our warfare. Be careful; there are many, even among so-called Catholics, who have basically tried to turn the anti-abortion issue into a political one. It's not; it's a spiritual and moral one, and the battles can only be won with the weapons from Heaven.
Our Lady, Mother of mothers, pray for us.
St. Gerard Majella, patron of expectant mothers, pray for us.
Sacred Heart of Jesus, have mercy on us.