I should add that I would not recommend a meander for basting if you are going to use regular thread. (I'm sure Jamie Wallen, when he recommended this, was using water-soluble thread.) Creating a large grid would make more sense since your friend could pull long sections of thread out as needed. The problem with machine quilting over regular thread basting is that it can become a lot of work trying to take out the basting thread, especially if the machine needle pierces the basting thread while quilting. If the batting can support it, I think the idea of quilting lines 10" apart and stitches an inch in length would be good.