If you can lay out your quilt sandwich on a table that is thin enough (my glass dining room tabletop is just right for this) you can clip your backing all the way around with big binder clips (from Office Depot or Office Max) and tape it with painter's tape or masking tape as well. Sometimes I use the basting spray but don't like it so much because it's difficult to reposition once it's sandwiched. It's always something.
Dana