Sorry to hear about the creak and groan. I haven't experienced anything like that on our 31, but I know what it's like from some other boats I've sailed on. It can be very distracting at night if you're a light sleeper like me. Some folks just get used to it -- like the idiosyncrasies of loved ones -- but for others it is akin to purgatory.
I've been thinking about your question, but still don't have a good answer. The best solution I've come up with would be to wedge some dense closed cell foam into any gaps between the surfaces (if there are any?). This might have the compound effect of reducing the wood-on-wood noise, as well as helping to absorb/dampen whatever noise remains. Possibly unsightly, though.
If there are no gaps wide enough to wedge foam into, maybe there should be and that is the problem? I.e., perhaps the wood components should not be contacting each other? If so, a small japanese pull saw, with the thinnest of kerfs, might be used to advantage to cut a narrow strip of offending wood?
Alternatively, the solution might be to bond the opposing wood together so there is no noise-generating friction between them. This might be done with thickened epoxy
injected via syringe into the thin gap (tape the area carefully to avoid spillover). I'm not as thrilled about this idea, though, because of the potential future need to disassemble cabinetry for maintenance.
Best of luck to you, and please report back if you find a solution.
P.S. I checked the Swan website for in-progress build photos, but it looks like Dave has expunged the records of that unfortunate chapter. I admire him for pressing on in the face of adversity and finding another path to achieve his objectives.