When we rented some crew hire cars for a detachment in Hawaii, I told the rather tasty little lady at the desk that my UK licence was only valid on Corvettes and Camaros in the US....
"Oh, gee, sorry sir. We don't have those - but we can let you have some T-birds if you like?"
Yes please! Actually, it turned out that the typical US tourists didn't like squeezing their 2 cubic yards of turquoise crimplene clad hamburger-backsides into the back of a 2 seat car, so the Thunderbirds were going for a song! Nice cars, but rather gutless.
Anyway, back to the plot - GS-alpha, if there's an RF/ATO such as Abbasair specialising in adding SEP Class Ratings to ex-airline pilots' licences, it'd be well worth contacting them.