All of this would seem to me to point toward a market for a business attire but not formal jacket that's kilt-length. It would have to be a bit more contemporary so the gauntlet section of the sleeve and the epaulets could be done away with. Something like your basic Navy Blue or Black blazer. Tweed seems relatively easy to come by...I have seen blazers with the patch type pockets that are somewhat removeable when making modifications. Perhaps following AllanH's instructions for modifying a sportcoat into a kilt jacket and using a Navy blazer as the raw materials?

This has me back looking at the Kilt Store's Charcoal Grey Crail Jacket as reference...hadn't noticed that they also can provide a kilt and waistcoat in the matching material...now that, to my mind, would be a sharp look.

Best

AA