Why aren't you spray basting???
I should add that an easy way to spray baste is to get a sheet of plywood and inexpensive sawhorses at the hardware store, and I would get maybe 6 of the best hand clamps they have. Set this up in you driveway when you need to baste. I'm really slow, but I could baste a twin sized quilt in 30 minutes max this way. Set up, tear down, and storage are all easy. Monetary investment is fairly minimal.
After learning how to spray baste, I have never pin-basted another quilt. Also, after using several different brands of basting spray, I would recommend biting the bullet and paying a little more for 505.