See the article Summer Camp for Boys by the Canons Regular of the New Jerusalem at AMDG.
The Canons Regular of the New Jerusalem is a relatively new religious order that celebrates the traditional Latin Mass with a semi-monastic life. They are also known for hosting symposia and for teaching the Faith via the classic philosophy of Thomas Aquinas. They have started a school for young men who are discerning a vocation to the priesthood, in a traditional, rigorous manner.
I haven't visited the Canons Regular for a while, but I understand that they have a new chapel at their priory where they hold daily Mass; Sundays they are at the Passionist Monastery nearby: see the website for details.
The Canons Regular are located in a somewhat isolated area, and so their existence isn't very well known yet.
Address of Priory. Click for a Google map. However, it does not show the correct address; instead take the winding drive just north of the round school building shown in the aerial photo.
1635 Kehrs Mill Road
Chesterfield, MO 63005
Passionist Monastery for Sunday Mass:
15700 Clayton Road
Ellisville, MO 63011