I thought about this thread yesterday when I was at Smith Rock and came across a Pack and Play (portable playpen) set up in the shade with a beautiful 7 month old baby girl inside and a dad, wearing his harness, holding a sock monkey puppet and entertaining her while mom was climbing. The dad said when the baby was younger they brought down her car seat, but around four months old that no longer worked. The key for them was finding a willing third person to go along so while two climb the other is with the baby and then they rotate.
Not sure if it was one of you we met, but wanted to pass on what they did to you newer dads.