Lease ends July 31, and I'm absolutely coming up against the challenges you mention... microchip shortage, customer demand. What's more, if I went Sportage again, I'd like the almost-announced facelift, which is reckoned for March availability, or, if I pushed up to Sorento, that's supposedly six months - even four months for a current-gen Sportage. The cars I'm looking at are Kodiaq and Tarraco, maybe Sportage/Sorento, maybe 5008/C4 Grand Spacetourer/CR-V. It's a perfect storm. I will have use of other family cars (Corsa and Seat Leon estate), so it's not a disaster, but still really tough to buy at the moment.
Anyway, it was sort of an in-principle question, notwithstanding all those issues - the idea of taking an SE base and loading it up to SE L equivalence to benefit from the extra boot space in a 5-seat model.
But I guess you're saying, even assuming that's not cray, the supply issues may be compounded further by a custom-spec of this kind (?).