I had the same idea you did about someone else helping Rey lift the rocks, except I wanted Leia to lift them. I think that could be a much better option. It would set up Leia training Rey in TROS, to make these movies seem more connected. It would show that although Rey has plenty of raw strength, as demonstrated in the rest of the movie, she still needs to learn to concentrate. And it would avoid deifying Luke’s character, by having someone who hasn’t shown much Force sensitivity before performing such an enormous task.