My 6 yr old grandson had the audacity to outgrow his backpacking sleeping bag. He is currently 49" tall & 44 lbs.  This Christmas present needs to be sized for next summer (growth) along with the warmth factor being able to handle his backpack trips to the high (cold) country in Colorado's Rocky Mountains.  My 1st issue is having trouble just identifying the correct sizing but thinking that a bag for a 5 footer might be good and secondly would like to find a warmth factor of 20 degrees.  Suggestions please?

Thanks & stay healthy