Fully comp always complicates the situation it seems to me; that is what is discussed, among everything else, in those sticky threads.
Some where in the mass of detail in those threads, most recently mentioned have been "Footman James" and "Ebike" as useful bike insurer brokers but I don't recall if that was for green card cover only for 12 months cover - probably was for fully comp because there are treaties which require any ins issued in the EU to be valid in any other bit of the EU.

I have "permanent" fully comp cover for taking a car to Europe; any broker will do this IMO at the time that your cover is up for renewal - that is when I put them on the spot (with the threat of taking my business elsewhere) and guess what .................. it gets done.
Far too many Brits accept everything that the insurance brokers/sales reps/call centre minnions tell them.
This 12 month cover for a car was charged at an extra £19 for the full year at last renewal.

For my bikes, I don't care; I have never had fully comp cover and if I drop one or other then I deal with it. Simple.

As for Turkey, you buy it at the border, same for the visa by the way.
Beyond there, I have no idea but it will be similar is my guess - there are certainly plenty of folks on here who have been there!!

Hope this makes sense.

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Dave