How to add a window seat here

Hi all,
I have this big window with a nice view on the garden but unfortunately no balcony.
I am searching for a seating solution that would be high enough to accommodate the radiator and also allow for ba nice view of the outside.

I cannot do anything custome built because the apartment is a rental and I don't have the means.

I was thinking of a very high bench but I can't seem to find any high enough.

So I looked into some kind of narrow table but I am afraid they won't be sturdy enough for a person to sit on.

What do you think? Any ideas?

Thanks

BTW, the height of the window sill is 85 cm.