You might also consider positioning your ironing board along side your sewing machine, at a right angle, to support part of the weight of the quilt. I am machine quilting right now, and I discovered this ironing board tip a while back and it really helps.
I also lower the height of my ironing board so it is the same hight that my sewing machine desk is.
The nice thing about using my ironing board is that it is right here and I can move it back "where it belongs" when I am done.
Dina