Duncan’s previous novels, “The River Why” (1983) and “The Brothers K” (1992), were countercultural best sellers, traipsing among such subjects as fly-fishing, baseball, the Vietnam War and, inevitably, spiritual questing. “Sun House,” reportedly 16 years in the making, outbulks even the 645-page “Brothers K.” It devotes 350-odd pages to the back stories of its characters — a mountaineer, a “bardic” folk singer, an actor, a rock star, a restaurateur, assorted cowboys — and then 400 pages to the vegetable-growing, cattle-ranching, whiskey-drinking, “spiritually awake” community they establish in the valley of the fictional Elkmoon Mountains.

Their 4,000-acre refuge has been violated by an evil multinational corporation trying to build a luxury resort, the Brokeback Ranch & Country Club, whose name the company shamelessly steals from Annie Proulx. The Elkmooners, “with faith in natural regeneration and no desire to turn a quick profit,” pool their not-so-modest resources ($750K here, $400K there, and pretty soon you’re talking about real money) to heal the valley and to market beef from animals slaughtered with love.

This eco-capitalist idyll gets a temporary setback when a young vegan communard sabotages the operation; some Elkmooners want her arrested, but they settle for subjecting her to a stern re-education, culminating in contrition and a penitential bite of steak. “I want to taste the body and the blood,” she tells them. This episode, a wildfire, a high-altitude rescue and a protracted death scene — featuring much communal humming and a too conveniently trapped-and-released hummingbird — fulfill the conventional novelistic requirement that things happen, though none of it quite amounts to a conventional plot.

Clearly Duncan — or his first-person narrator, known only as the Holy Goat, or “HG” — aspires to nothing so thinky. “The millionfold story” of the community “is untellable, and what a relief!” he writes. “Now I, the Holy Goat, can turn to whatever I’d most enjoy telling.” This is actually another character putting words in his mouth, but no matter: HG considers his characters his co-authors, and the whole novel is evidence of a let-’er-rip methodology.

An Elkmooner named Risa — the Sanskrit devotee and an improbable paragon of generosity, insight, esoteric scholarship and “gat-toothed” fetchingness — tells HG why the valley can’t be bounded by the classical, left-brained novelizing that created Mansfield Park. The community, she says, “is a tiny but estimable fraction of Vedic cosmic illusion, a toothless Zane Grey yarn undergoing feminist and metaphysical revision … a barrage of poetics ranging from free verse to cowboy doggerel to the godsongs of Maharashtran poet-saints … to late-medieval mystic chants to … the sometimes heart-rending chatter and songs of our own children. What single genre could cover all that?”