I’m sure you’ve already thought of it but what you need is a custom mounting frame/bracket, which if you can find a motorsports fabrication shop, wouldn’t be difficult to scratch up.
Just out of curiosity I plugged “Recaro E21” into google and up popped Aardvark Racing, who specialise in Recaros and old Beemers. Might be worth calling them and see if they have any idea what you could do, long term.
BTW, wife sounds like a keeper. But then if she’s suffered through this job and still with you, you already know that. 😉