Ok, I'm an idiot.
I did what Greg said and moved the pad directly under my hamstrings and did 3 sets of 10 with only some slight discomfort in the lower back on the last set. Now I just need to work these in more often. About the only thing I can say about having the pad there is I had visions of my head slamming into the ground.
Thanks for all the input.
"And for crying out loud. Don't go into the pain cave. I can't stress this enough. Your Totem Animal won't be in there to help you. You'll be on your own. The Pain Cave is for cowards.
Pain is your companion, don't go hide from it."