Here's an interesting pondering:
Would it be possible, if you had already made the Heroic Act of Charity, to then do the Consecration to Mary according to St. Louis de Montfort?
For reference this is what the 30 day Novena for the Holy Souls book has on the Heroic Act:
The Heroic Act of charity is an offering of all works of satisfaction we may gain during life and all the suffrages that may be offered for us after death. We place this offering in the hands of Our Bless Lady, leaving her to apply it as she sees fit for the release of the souls in purgatory.
This does not prevent us from working or praying for ourselves, our relatives, or others. This act does not oblige under pain of sin, and it can be revoked at any time. It may be without any special formula.
A key advantage of this heroic act is that it increases our eternal glory, the possession in a greater degree of God fall all eternity.