One of Shakespeare's contemporaries, the dramatist Ben Jonson, published an English Grammar in 1640. Chapter XII, Of Comparisons, discusses the comparative and superlative degrees for adjectives and does not mention the adverbs "more" and "most".
However, the chapter "Of the Syntax of Adjectives" points out that (bold emphasis mine),
Oftentimes both degrees are expressed by these two adverbs, more, and most: as more excellent, most excellent. Whereof the latter seemeth to have his proper place in those that are spoken in a certain kind of excellency, but yet without comparison: Hector was a most valiant man; that is, inter fortissimos.
Furthermore, these adverbs, more and most, are added to the comparative and superlative degrees themselves, which should be before the positive:
Sir Thomas More :
Forasmuch as she saw the cardinal more readier to depart than the remnant; for not only the high dignity of the civil magistrate, but the most basest handicrafts are holy, when they are directed to the honour of God.
And this is a certain kind of English Atticism, or eloquent phrase of speech, imitating the manner of the most ancientest and finest Grecians, who, for more emphasis and vehemencies sake, used so to speak.
So not only was it acceptable, it was also good style.
Source: Jonson, Ben: The English Grammar. Edited with an Introduction and Notes by Alice Vinton Waite. New York: Sturgis & Walton Company, 1909.