Ideas for a frost shelter on a steep bank?

I have an extremely steep (45° or thereabouts) rammed earth bank north of my annual vegetable garden, circa 1.2-1.5 m tall, currently covered in grasses. I have noticed that when we have a frost, it sits longest in the veg garden location – I sense that the cold air is flowing down the hill so I am trying to think of some plants I could plant to might be able to give a yield but also act as a shelter from that cold, frosty air. Sadly, I cannot amend the bank profile (it’s part of a flood defence), nor can I terrace it – it isn’t wide enough. It is an ugly feature in my garden that I have to endlessly work around.

Any plant needs to be compact (very much shrub and not tree), happy in the cold and able to live in such a steep location (which in turn means it is almost impossible for me to mulch the plant meaningfully). On the upside, it faces south/southeast, so it gets a solid amount of sun in the summer.

I wondered if anyone had any ideas. The soil there is poor, and stony, and we’re SW UK, circa zone 9.