Making 12 cubic yards of xeric alpine soil....any help?

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Hi all,

I am a new member of NARGS and I am so happy to know about this organization. I have always been interested in rock gardens, and now I am gonna be able to make my dream come true because me and my partner finally have our own house in Dallas TX! I will build a 12-cubic-yard berm with mossy sandstones on my south-facing front yard. The berm height will range from the grade level (where I will plant more water-needing plants) to about 24-30 inches at the very top of my "hill."

Now, I read hours and hours (well, let's say days and days) about desert alpines and the type of soil I should create, and I came to a conclusion that everybody has a different view on the best soil recipe!
Nonetheless, I found out there are essentially two recurrent recipes mentioned online.

Recipe option #1:
1 part of grit (I would use expanded shale)
1 part of sand ( I would use coarse concrete sand)
1 part of peat (I would use a mixed soil that is available at the same local quarry where I will also get the sand and the shale. It consists of a mix of topsoil, sand, and compost--this compost made of decomposing vegetation and manure)

Recipe option #2:
1 part of grit (expanded shale)
1 part of sand (coarse concrete sand)
2 parts of peat (again, mixed soil)

Mulch I intend to use:
1/2" limestone gravel

Since I am building a huge rock garden by creating a berm with 12 cubic yards of soil, I think it is imperative that I know what the perfect soil should be to grow my future plants! In my personal opinion, I believe that I should use recipe #2 because this recipe was mentioned in other websites by people who prevalently live in the South. For this reason, I believe a "too sandy and gritty" soil as in recipe #1 would be hard to maintain in North Texas, while it would probably be perfect for areas with more average rainfall.

Now, here with the plants I would like to grow:
Achillea ageratifolia
Agave neomexicana
Aloinopsis spathulata
Alyssum montanum
Anacyclus depressus
Arenaria sp.
Armeria maritima
Aster oblongifolius
Callirhoe involucrata
Coryphantha echinus
Delosperma ashtonii
Delosperma cooperi
Delosperma nubiginum
Dianthus
Escobaria (Coryphantha) vivipara
Escobaria leei
Escobaria orcutti v. koenigii
Festuca glauca
Helianthemum nummularium
Hirpicium armeriodes v.
Hymenoxys scaposa
Iberis sempervirens
Nananthus transvaalensis
Nierembergia gracilis
Osteospermum 'Avalanche'
Penstemon pinifolius 'Compactum'
Penstemon virens
Phemeranthus (Talinum) calycinum
Phlox grayii
Pulsatilla vulgaris
Rabia albipuncta
Veronica spicata 'Glory'
Ruschia pulvinaris
Saponaria lempergii
Titanopsis calcarea
Verbena peruviana 'Red'
Zauschneria california 'Wayne's Select'

Opuntia polyacantha ‘Taylor’s Red’
Opuntia aurea ‘Coombe’s Winter Glow’
Opuntia rhodantha hybrid ‘Grand Mesa Peach’
Pediocactus simpsonii
Echinocereus ‘White Sands’
Echinocereus coccineus

Of course I am not going to buy them all, but I will select from this list.
What soil do you guys use and what do you suggest for my project?

Thanks!

Rino