If our outdoor Masses (aka Street Mass) were meticulously prepared in this way, I would consent to offering one!
Even Fr. Anscar Chupungco, OSB has this to say about the issue: "There is a mistaken notion among some people that when the liturgy, including the Eucharist, is celebrated outside the church building, we need not worry about liturgical propriety regarding vessels, vestments, and books. Such attitude projects the wrong view that the Eucharist outside the church, especially in shopping malls and prisons, is less noble than the Eucharist celebrated in churches and cathedrals. It is always useful to remember that the worth of the liturgy does not rest upon the place where it is celebrated but upon the presence of Christ in his community.
"I had the occassion to participate in a Sunday Mass in an airport, which is under the ecclesial jurisdiction of a rather wealthy diocese. To my chargin the priest used a leaflet for the readings, which he devoutly kissed after the gospel. The Sacramentary was a worn-out book that antique dealers would be eager to buy. The chalice was a miniscule of a vessel and the ciborium was an orange-colored plastic container. The table was so low that the priest had to stoop to read the Eucharistic prayer. It crossed my mind that his parish probably had all the appropriate vessels and furnishings, but that he had reasoned that, after all, this was just a Mass in an airport, so why bother to bring the good things reserved for a church?" (A. Chupungco, What, Then Is The Liturgy: Musings and Memoir, 159.)
Pictures of the Outdoor Masses from the Chartes Pilgrimage 2011