Most "authorities", including the ones you cite, regard the combination of the adverb "well" and the past participle (e.g. "documented") as a compound modifier in the same way as "the red-brown dog".
The American Heritage® Book of English Usage, 1996 has a discussion to this effect. The whole article is under
Among other things, they write
"Compound adjectives formed with an adverb or a noun and a past participle are always hyphenated when they precede the noun they modify: well-kept secret, above-mentioned reason, helium-filled balloons, snow-capped mountains."
They also write
"If the adverb ends in -ly in an adverb-adjective compound, the hyphen is omitted: a finely tuned mechanism, a carefully worked canvas."
And this is where my problem lies (and that of an English teacher in my distant past). If you take the two examples "a finely bound book" and "a well bound book" (my lack of hyphenation in the latter), you have an identical grammatical construction, namely an adverb modifying a past participle (adjective) which in turn modifies a noun. There is no sensible reason to hyphenate one and not the other. All parts of speech are doing their normal job quite happily without the need for a hyphen. The syntax and word grouping are perfectly clear without hyphenation.
There is an entertaining article in agreement with my position under
Another more serious one is in the GSC Guide to Authors under
http://www.nrcan.gc.ca/ess/pubs/guide/p ... hen_e.html
In the latter, it says
"[Do not hyphenate] ... if the adverb in a compound adjective cannot be misread as an adjective modifying the noun (the use of hyphens with adverbs ending in ly and with the adverb 'well' are the most common errors):"
Indeed, the whole of the GSC article strikes me as being well founded (primarily, of course, because it agrees with me).
Reply from Phil White (Munich - Germany)