Sleeping pad sizes seem to be standardized somehow like this:
normal: 183cm x 55cm
long: 195 cm x 65cm

I.e. the longer is also wider. I need extra length but not the width. (It creates complications with the limited tent floorspace.)

So, do you know any sleeping pads with dimensions around 195 cm x 55cm?

So far I have really only found two: Robens Vapour 60 and Robens Primavapour 60.

These work alright for warm weathers but a pad with higher R-value is still missing from my radar.