Blooie. I have the towels on top b/c it was suggested to me by folks on this site. I was initially concerned that the towels would absorb heat that could go to the chicks, but I saw and heard that many layer the top of the cave and cover with straw. I cut my towels to fit now so there are no places to get stuck (that I am aware of) Two nights with the new set up and everyone is well. My main concern was that someone would stick their head through the wire shelf and directly onto the heating pad, but so far so good. I will switch out the 4x4 blocks for 6x6 blocks when they get a little taller so I don't have anyone hang themselves on the shelf.
After breeding equines for years (VERY stressful and expensive) I have been looking forward to chickens, but I guess I am true to form b/c I am stressing plenty about these chicks. The silver lining is no matter what happens I won't end up with a 5K vet bill

. I am loving them, I just dont' want to lose anymore of them. Thank you for your wisdom and advice