You’re missing the “+2” part of the Elan description.
I looked it up the other night, it was as I suspected. A standard Elan (like Mrs. Peel drove) is smaller than a Miata NA in all dimensions. A +2 is bigger. A little wider, a touch more wheelbase, a skosh more overall length. I’d say it can be done, by the letter and spirit of the law, but what do I know?
#289 1984 Corvette Z51 (the road goes on forever…)
#111 Tradewinds Tribesmen VW Passat Inde ‘20 (‘21 too) Thunderhill ‘22!
Gone but not forgotten, #427-Hong Kong Cavaliers Benz S500: formerly known as OMG Racing #140
Other foolishness: Finisher of Hell on Wheels (Jaguar) IOE (Humber)