Seaberry for fruit tree protection?

With the observation that Seaberry generates very little shade underneath it, but can not tolerate being shaded out itself, I had an idea for a way of planting out a mixed orchard. Please tell me if this makes sense.

We have a very steep 2 acre hill, all grass. I've been planning for establishing various fruit/nut trees, shrubs, and useful herbaceous dudes in rows, on contour. There's major deer pressure though and I have concerns about soil erosion on this steep hill.

If I planted hundreds of seedling Seaberry on contour, in rows, I'm thinking I could then plant my fruit/nut bushes/trees directly under the Seaberry. The dappled shade should hopefully be a nice condition for the young plants to grow and maybe the Seaberry thorns will protect them from deer/rabbit browse. When the trees grow sufficiently they'll likely shade out and kill the Seaberry, which is fine by me, especially with the accompanying nitrogen nodule release from root dieback.

Has anybody tried something similar? Do you think it'd work?

A couple considerations from my experience:
I planted it between fruit trees and it spreads like crazy via long runners. Granted, it does only seem to spread like this through wood chip beds. Not out into the surrounding grass at all (or at least it gets mowed and I don't ever see it escape the chip beds.)
Also, it's not too terribly thorny IMO. I tend to forget it even has thorns until I get too vigorous picking Japanese Beetles off of it and get the occasional poke. Those beetles love it by the way.

I'm just now encountering the long runners and how much they enjoy deep wood chip...rethinking my decision to plant these close to established veggie beds :-(

I've heard the runners can be pretty impressive! I'm thinking I wouldn't be horribly opposed to spread - the veggie garden on this property is probably 100 yards from this hill. Might start to get tough to mow..hmm... maybe a comfrey rhizome barrier, or do you think the SBT would just blast through that?