I am absolutely confident a Professor of Marian Theology and a member of the clergy knows what he is talking about.
Your catechism quote covers religious, clergy and the vocation of marriage, marriage being a special sacrament in itself that two people share and is witnessed in public and recognised by the Church in public.
Your quote does not cover the topic I have raised.
With regard to the way we can choose to entrust ourselves to the Virgin Mary, people can go the route outlined by St Louis de Montfort over 300 years ago,
Or people can go other routes, including acts of entrustment via prayer and other routes outlined by other saints.
It is up to the individual, and what suits them best. And neither way is better or worse.
The end result is entrusting ourselves to Mary, and living our lives with regard to that.
There are Public Associations of the Faithful who include entrustment to Mary as part of their formula of prayer, as an act of prayer, a simple prayer repeated during group meetings. There is one such association, formed for clergy, by clergy that uses a prayer of entrustment, as compared to a 33 day long preparation. A person joining the Legion of Mary, a recognised Public Association of the Faithful, is free to go any path they wish. For example.
I have found that preference for either way seems to be quite regional.
We renew our baptismal promises every time we attend a baptism and at different times over the Liturgical year.
There is a danger in people such as the OP, thinking there are too many roadblocks or hoops to jump through when in reality, a private devotion can be taken up by anyone of any denomination at any time. I am sure Mary is waiting and wanting to gift those yet to enter into full communion with the church , her love and intercession. And all they need to is ask.