Hugelculture orientation, shape and avocados in zone 7a

Hi Everyone!

I am planning to build a 180cm = 6' tall hugelculture bed/berm. I'm on a slope facing south east in zone 7a, the average annual precipitation is 118.13mm (4.65in).

Sepp Holzer says that hugelculture berms shouldn't be on contour to avoid frost pockets on the uphill side of the berm, but slightly angled to the contour lines to allow excess water and  cold air to flow around the berms.
Is this a concern in my non Alpine climate in zone 7a?

I want to grow an avocado tree, but my cliamte is too cold, unless I build a sunscoop, orient it's opening to the south on the slope to avoid cold air accumulation inside the cresent and I put rocks on the side of the inside of the C shaped berm which would be the thermal mass that keeps the tree warm in the winter and at night.
Is this a valid idea or should I forget about avocados?

As of now its hard to grow avacados in any zone lower than zone 9.  But there are people working on that, and you can be one of them if you want, but it would be really hard.