Sorry, not my speciality.
I just know that a delta can be landed nose up at a crawl.
There's no magic to deltas. As they get heavier, they get faster. Yes you can go high alpha and land slow but not as extreme like this and what makes things worse: You don't even have to fly it high alpha to get it crawl in RC8.
Mine lands faster than this and the nose is that far up that I actually have to add down elevator so the wheels make contact before the tail woth my real model. The mirage in RC8 has wings filled with helium.