I came in to mention Cleveland Whiskey, but thelurkinghorror beat me to it. Having sampled it, it wasn’t terrible, but had a long way to go before it can stand toe to toe with the real thing. Bit of a metallic taste, but quite nice with some ginger ale.
And rum ages even faster in the Caribbean and elsewhere that they distill and age rum, which is why a say… 15 yr old spirit will be a pretty ancient rum, a well-aged Bourbon, and a middle-aged Scotch.
I wonder if anyone’s tried aging bourbon somewhere like Brownsville, Phoenix or maybe somewhere in Florida?
If temperature swings are the thing, I’d think you could do better than Kentucky by going west into Kansas, Oklahoma and N. Texas. We routinely see nearly 90-100 degree annual temp swings.
Ranger Creek makes several whiskeys. I’ve had the Rimfire. IIRC, the age statement was 6 months under the Texas sun. It had plenty of wood to it.
I wonder if the liquid could be run through a cone of powdered burnt oak, like percolating an herbal extract.
Seems like the most practical solution would be to put the barrel of whiskey into a time machine and send it back to forty years ago.
And then drink whiskey that’s negative forty years old? Yecch. 
Im not certain just how important temperature swings are though. Obviously it has a role but there is so much more involved. It’s probably no coincidence that many of the best made whisky’s are from relatively stable(and mild) climates. There is, as yet, no real substitute for time. Aging whisky well is still an imprecise science imo.