Rik,
Otoh...if you are not offroading, we here in the Colonies do some
seriousazz long distance driving regularly, without a lot of concern
over flats/spares, etc.

The spare you have will get you quite a ways down the road, albeit
at slower speeds, in order to find a metro ctr and get your flat
fixed. Many of us are riding around on fixed flats here in the US:
we get a "patch" done, inside the tire. The patches last longer than
the tire tread and while they slightly reduce the load and/or speed
rating, it shouldn't present a huge problem. Or, one could get it
patched and motor on to a bigger metro ctr and cough up for a
new replacement tire.

Not knowing your definition of what "especially as I undertake long
trips on the continent" ...really means, I don't quite understand your reluctance.

I've driven all over England, Scotland, Wales, Germany, Belgium, France, etc., in
rental cars, and never had the misfortune of a flat; nor did I worry about that possibility.
My 25cts is up...
GL,mD