I go somewhere else to pin baste a bigger quilt. My public library's meeting room has tables that can be shoved together, and our historical society has a huge table that's often used for buffets. I can tape the backing to the laminated tops of these tables and then not worry about stabbing them with pins. My local quilt shop has a new class space with tables. It's not in use all the time, but I imagine the owner would let me use it for pin basting.
Another thing I do, which is hard on the back, is to lay the whole thing out on a bed and use a couple of old cutting maps underneath. I move those around carefully as I pin.