The world premiere stage adaptation of John Kennedy Toole’s picaresque, posthumously published, Pulitzer Prize-winning novel “A Confederacy of Dunces” is very much like its lead character, Ignatius Riley: flamboyant, overstuffed and discursive — but also, at times, fascinating and fun. Much of the appeal comes from Nick Offerman’s terrific turn as its slob/snob hero, tapping into the perfectly-timed deadpan he used to great effect on NBC series “Parks & Recreation.” Offerman endows this arch and effete Falstaffian figure with glimmers of fear, loneliness and tenderness in his perpetual revolt against the modern age.

But if the exuberant-yet-corpulent production at Boston’s Huntington Theater (with some significant commercial names attached, including Steven Soderbergh) is to move forward, some dramaturgical Slimfast is needed. Of course, that risks challenging the book’s fans, who are devoted to each eccentric character and meandering episode.

Playwright Jeffrey Hatcher has already done an impressive job of editing and shaping the story for the stage, retaining its essence as well as some of its dandiest dialogue. But more work still needs to be done to keep new audiences beguiled by the adventures of this proud and mammoth misfit, trapped by the extravagance of his own imagination.

Director David Esbjornson keeps the traffic of the show’s many characters and plot lines as smooth as possible with a stripped-down, self-aware and transformational approach. It only works some of the time.

Indeed, the play begins with a bare stage, as Offerman simply appears as himself, wearing nothing but a big bushy moustache and his underwear. Cast members then slide him into the fat suit, adding items of clothing to create Ignatius’ iconic look: giant tweed pants, unlaced boots, plaid flannel shirt, suspenders, muffler, and Ignatius’ signature hunter’s cap with the flaps down. (The hat gets a round of applause.)

Then the world of New Orleans in the 1960s emerges — a world in cultural, social and political flux on Riccardo Hernandez’ minimalist screen-centric set, with atmospheric touches provided by Sven Ortel’s projections. Onstage trombonist David L. Harris and pianist Wayne Barker add musical notes for the countless transitions.

At the heart of the rambling tale is the relationship between Ignatius, a fastidious, hygienically-challenged, imperious outsider, and his doting, exasperated, muscatel-loving mother (Anita Gillette, wonderful at being looney, warm and conflicted.) Circling, converging and ultimately piling up on stage are the denizens of NOLA: Claude Robichaux (Ed Peed, splendid), an elderly gentleman who courts Mrs. Riley with his Southern Comfort charms; the inept Patrolman Mancusco (Paul Melendy) on pervert patrol; the beleaguered Mr. Gonzales and the swishy Dorian Greene (both played by Arnie Burton).

At the Night of Joy Bar — one of the central settings of the book — sit the cynical sweeper Burma Jones (Phillip James Brannon, who has to cope with some awkward racial material); Darlene (Talene Monahon), who aspires to stripper stardom with her cockatoo; and dominatrix bar owner and porn supplier Lana Lee (Stephanie DiMaggio, who also plays Ignatius’s old liberal college chum, Myrna Minkoff, with radical affection).

Other standouts are Lusia Strus as brassy Santa Battaglia, who goads Mrs. Riley into institutionalizing Ignatius, and Julie Halston, who take nuttiness to a new level as the ancient Miss Trixie.

It’s quite a crowd, and at times the gumbo of a production turns to goo as the performances rely on cheap laughs and the staging swerves out of control. But then Offerman’s Ignatius returns to rise above it all with an outlandish pronouncement, a verboten thought or a critical look — until finally, gloriously, he makes his final break from this mad, mad world.