The good quality masks are not that expensive and I'm pretty sure they're available from Amazon.
Another thing people can do is tape a sheet to a garage wall, pin the quilt sandwich to the sheet, and spray with the garage door open. This can also be done outside. If a closed garage door is not suitable for a backdrop, one can purchase a couple of panels of insulation foam (4'x8'), duct tape them together, prop them against a garage door or the side of the house, and pin to them. Several people on the forum have done these things and even posted pictures. Sure beats getting down on the floor!