What about a version of Baptism of desire which would be God giving the soul the actual sacrament of Baptism while dispensing the need for water ? The person would then be incorporated into the Church, under the jurisdiction of the Pope, and have actually received the sacrament of Baptism itself, but in an invisible way. I'm not sure if this is compatible with sacramental theology though.
I know that this is probably not what a lot of the people who believe in BoD hold, but this seems to me like it would make it compatible with all of the dogmatic definitions on EENS.
Also, since Latin doesn't have definite articles, maybe the Council of Florence meant that it is only in the Unity of the Body that some of the Sacraments profit for salvation, which could be excluding Baptism.
For instance, if I say Occurrit ursis, how do you know if the person met all the bears, or only some bears ? I might be wrong because I'm no Latin expert though.
"If anyone says that real and natural water is not necessary in the sacrament of baptism, let him be anathema" It is in Denzinger somewhere. I think Trent. No water, no sacrament. To say that you can have baptism without water is about as ridiculous as to say you can have marriage without a bride.