Does such a critter exist? Or is there an alternative? How about the muskrat?
Hawbaker muskrat. One "California" clip, one wharncliffe. Unfortunately, not many (if any) are currently being made, but you can find NOS ones in a few places, or just keep trolling eBay. Queen, Schatt and Morgan (by Queen), Robeson (by Queen), Northwoods (under contract by Queen), Canal Street, Bulldog, and Case all made Hawbaker specials. The Queen made ones and the Canal Streets are probably the easiest to acquire. The Case Hawbaker Specials are all vintage (70's and early '80's), and command high prices (and aren't stainless). The cream of the crop is the 2004 Case/Bose muskrat in 154CM, but if/when you find one, it won't be cheap. All are 3 7/8" or 4" depending on the model or who's holding the ruler (the Case/Bose is 3.75").
As others have mentioned, a wharncliffe trapper also offers a clip and a wharncliffe blade. Case makes/made them in mini (3.5") and full (4.25") size (and tiny - but I doubt that interests you). If you've got an extra $450 or so lying around, wait until November for the Case/Bose annual release.
I like the looks of the Queen splitback whittler but is that an EDC knife?
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That and I guess I am unsure of the splitback design. It is new to me and I worry that the mainspring will break more easily than an other style of traditional. Not that I plan to use the splitbacks secondary blades hard. The main blade will be called upon to cut plastic straps (no metal in them), cardboard and, occasionally, my lunch.
The Queen whittler is a fine EDC knife. No need to worry about strength/durability. The coping blade won't be quite as stout as a stockman's sheepsfoot, but it's by no means fragile. It's a very pocket friendly EDC, but quite a bit smaller than the 4" knife you're looking for.
Or you could just stick with a stockman. They're not as common, but there's stockmans out there with pen or short clip blades instead of the spey. Most common is the Case 63032. And its predecessor, the 6332, as well as the 6318HE, but those two will only be found in carbon steel (not stainless).
Camillus had their 72 "carpenter's whittler" patter, which is a tapered swell center with a large clip, coping, and short clip arranged like a stockman (not a whittler as we define it). 3 5/8"closed.
Queen made some stockmans with a long California clip, sheepsfoot, and short clip under the Robeson Mastercraft name. 3 7/8" or 4" closed...I can't remember exactly.
Then there's the daddy of all those stockmans, the Queen/Schatt and Morgan File and Wire stockman. ATS-34 main blade with sheepsfoot and short clip (those are 420HC). A bit hard to find though. 3 7/8" closed.
