"Down-gyved" sounds more like it's gibberish from the Jabberwocky than actual English, and that's honestly true of a lot of Shakespeare nowadays.
I think we'll have to agree to disagree on whether this is "pretty clear" or "only passably comprehensible due to the surrounding context". It's hard for me to consider something "pretty clear" if I could replace one of the words with actual gibberish and the meaning wouldn't change to me; "Ungart’red, and down-barboodled to his ankle" is equally "clear".