One liturgical "rule" that is sometimes urged against traditionalists is that we should celebrate Mass as the Pope does. As a "rule" it can be turned as a useful pointer to what is definitely not prohibited.
Liturgists who said that you should not say the Rosary during the exposition of the Blessed Sacrament, or that you had to say the Divine Praises before the Benediction was given, had to go quiet when both of these things started happening routinely in St Peter's. A little known but delightful example was told to me by a priest friend from the latter days of Pope John Paul II. Unable to celebrate the academic Mass, the Pope was seen to attend and say the Rosary during Mass.
The New Liturgical Movement has a most interesting post that offers a similar "Who says we can't?" opportunity. The Redemptoris Mater chapel was consecrated in 2005. It is used by the Holy Father for the annual retreats and for spiritual conferences in Advent and Lent. Have a careful look at this recent photo which shows the chapel as arranged under Pope Benedict:
That is indeed a tabernacle on the altar. If it is not obvious from that detail, other pictures at the NLM's post asking if it is a barometer of the liturgical shift show that the altar is clearly set up for celebration of Mass ad orientem.