gspnole. Welcome to the GSP club of destroyers! I believe I can be of some assistance because of the wonderful help I received over the SAME issue! My GSP pups, 2 of them, are 14 months old now. By the time they were 9 months old, they had torn up at least 3 or 4 beds. The last one was quite expensive, so I turned to the forum for advice. This is what truly worked for me:
Get an old, (or new) queen or full size comforter, along with a couple of other small blankets, throw them all in there and call it good!
I purchased 2 $20.00 queen size comforters off of amazon.com, and then discovered that walmart carries 20.00 comforters too! Seriously, throw the pillow shams in there too, more than likely your GSP will tear up the sham, but that's okay! That's what it's there for. I would love to advance mine to a more comfortable bed, (or what I think would be more comfortable), but these two LOVE to move the blankets around and make their own little bed nest. It's not pretty, but it's practical! Honestly, neither has touched the comforter, they go after the smaller shams or smaller blankets that I throw in there. I have had the bedding for at least 4-6 months, and have been quite pleased!! I am hoping to advance them to their forever beds by the time they are 3 or 4!