I am answering the question :
"Are there any reformed persons who argue for such a position" that is to say who "reject sensus unum and yet still affirm biblical inerrancy from a view of sensus plenior" ?
I define sensus unum as the concept that any biblical text has a plain meaning, an obvious meaning and a single meaning.
I define sensus plenior as the concept that any biblical text may have several layers of meaning, or multiple meanings.
I define myself as 'Reformed' in that I agree with the the doctrine and the practice (largely) of such as Martin Luther, John Knox and other such.
Scripture is referred to by Paul the Apostle as 'inspired' II Timothy 3:16, which word is θεοπνευστος theopneustos, 'God-breathed'.
But Peter declares that some persons - unlearned and unstable persons - 'wrest' the scriptures to their own destruction, II Peter 3:16.
It is perfectly clear that in the matter, for example, of the turning of water into wine at Cana of Galilee, that there is a meaning to the whole passage. Underlying the narrative, the statement of historical fact of water being poured into stone pots until they were full, then the water being drawn out; and in the drawing out of the water, it is found to be wine - there is clearly a meaning beneath.
This was not a display of supernatural ability just to demonstrate supernatural ability. It is clear from the development of the book written by John that a spiritual truth is being expressed by the miracle - or 'sign' as σεμειον semeion is better rendered.
What is being expressed can be seen from the context and from what has just happened in John's unfolding text and from what will follow in John's proceeding narrative.
There is a clear meaning - a single meaning - from the supernatural sign.
But buried in the narrative is the fact of water being 'made' wine, and the word ποιεο poieo is used to convey that fact.
Which is the same word used by Paul to convey that Jesus Christ was 'made' sin in the offering up of himself in sacrifice, II Corinthians 5:21.
The demonstration of water being made wine, that is to say the fact that water had something added to it, and thus it became other than it had been, that thus there was - suffused throughout the whole body of water - something else which changed the character of that body of water : conveys something profound in relation to the other use of the word ποιεο poieo in Paul's epistle.
Thus, as a 'reformed' person I would personally argue not that the Cana miracle has multiple explanations in and of itself (for there is but one true and spiritual explanation of the meaning behind the miracle) but that there is more in the text to be seen.
For it is God, the Spirit - the Divine Person - who has inspired these most holy writings. And his masterful, brilliant, sensitive, artistic and immensely competent ability is seen throughout the passages, the texts the words - and even to the very individual letters upon the page.
There are layers of revelation in these God-breathed scriptures, is how I would express the matter. Layers of revelation and depths of profundity are encapsulated within inerrant and infallibly communicated documentation.
But one must be wary, for many foolish and unlearned persons wrestle with these holy writings and, in so doing, they do injustice to the words and they do detriment to themselves.