I think I've formulated a new apologetics argument that should prove fun and (hopefully) fruitful when talking with Protestants. Basically, the way Protestants view the Sacraments of Baptism and Eucharist is similar to how Paul describes the reason for Head Coverings in 1 Corinthians 11. The result of this line of thinking would not only force Protestants to make Baptism indistinguishable from Eucharist, but also to 'raise' Head Coverings up to the level of a new Sacrament in itself. Let's see where this goes.
In the Protestant mind, one of the chief errors of Catholicism is the Catholic claim that Sacraments cause an actual change within a person who uses the Sacraments properly. Protestants will say things like "there is no way just pouring water actually washes away sin," which is understandable because it's partly correct. But what is ironic about this is that most Protestants would believe that the Bible actually imparts saving effects upon a person, even though the Bible is 'only' paper and ink. What Protestants miss is that Baptism is not 'only' water anymore than the Bible is 'only' paper and ink. There is something else at work, namely the Holy Spirit! So if the Bible can actually impart spiritual benefit upon the properly disposed person who reads it, similarly Baptism and Eucharist should (logically) be capable of doing the same.
While Luther (and to some extent Calvin) could be fine with Baptism actually causing saving effects upon a person, the next generation of Protestants saw a few glaring problems/contradictions with this. As with all heresies, theological errors are much easier to get started while the truth-error balance is still in flux, before the actual logical and theological consistency gets worked out. Once the heresy has become accepted, then the actual coherence and proof texts can be sought, and any 'modifications' made. Generally speaking, the Protestant trend has been to reduce Baptism to merely an outward testimony of an inner reality which has already occurred. Protestants believe this for three main reasons: (1) to say water actually causes change is seen by Protestants as Catholic superstition (despite the fact Protestants treat the Bible in a 'superstitious' manner by that same logic); (2) to say Baptism saves is not easily reconcilable with the claim faith alone saves (which erroneously categorizes Baptism as a "work" [of the Mosaic Law] just like circumcision); and (3) to say Baptism saves conflicts with the notion that justification is a legal evaluation of a person's past, not a matter of a present inward transformation (despite the fact the Bible describes forgiveness of sins in terms of inward change). With this background in mind, we can get inside the mind of a Protestant and thus can proceed to the main argument.
My argument is that the Protestant view of Baptism and Eucharist as being merely outward testimonies of what Jesus has already done for them runs into two problems. The first problem is, if Baptism outwardly proclaims Jesus' blood has already washed away their sins, then how is Eucharist much different given that it also outwardly proclaims Jesus' blood has already washed away their sins? I'm sure Protestants can use all sorts of flowery language on how Baptism and Eucharist emphasize different parts of Jesus' saving work, but in the end both are really outwardly testifying to basically the same things. (What could they possibly do to answer this, maybe drive an artificial wedge between Jesus' blood justifying versus it sanctifying?)
The second problem is, why wouldn't other similar commandments in Scripture be able to fill the same role as Baptism and Eucharist, for example Head Coverings. Right in the middle of Paul's discussion on the Eucharist in 1 Corinthians 10-11, Paul speaks of the issue of Head Coverings in some pretty strong language:
Follow my example, as I follow the example of Christ. I praise you for remembering me in everything and for holding to the traditions just as I passed them on to you. But I want you to realize that the head of every man is Christ, and the head of the woman is man, and the head of Christ is God. Every man who prays or prophesies with his head covered dishonors his head. But every woman who prays or prophesies with her head uncovered dishonors her head - it is the same as having her head shaved. It is for this reason that a woman ought to have authority over her own head, because of the angels. Judge for yourselves: Is it proper for a woman to pray to God with her head uncovered? (1 Cor 10:1-15, trimmed for length only)
Now it is clear that HCs don't cause any actual change in the woman, so what we see is that HCs are acting more as outward testimony of what is already inwardly true. It is clear that HCs do tie into salvation as well, given Paul's reference to "because of the Angels" (either meaning Angels are truly present during Liturgy or else this is a euphemism for the Priest as God's messenger), as well as the context of Liturgy, and the subordination of Jesus to the will of the Father, mystically similar to how a wife is supposed to be subordinate to her husband in some real sense. Given this, it only makes sense for Protestants to classify HCs as a genuine 3rd Sacrament, fulfilling the same Protestant qualifications as Baptism and Eucharist.
These two problems are both plainly absurd and thus testify to the falsity of the Protestant view of Sacraments. Not only has no Protestant denomination ever held that HCs are Sacraments, it would be silly because then Liturgy would be an outward sign (Head Covering) taking place during another outward sign (Eucharist). Combined with the one time (even optional) use of Baptism, the infrequency of the Eucharist in Protestant liturgy, and the neglect of Head Coverings, we see the Sacraments have little place in the Protestant life...which explains why they've elevated a man with a secular doctorate degree as the central focus of their liturgy, where this priest dispenses their own super-sacrament in the form of a glorified Bible study, being "fed by the Word" (in this case the words of the minister's heart).