My snake is 2 1/2 years old 46 inches and 206.9g. I looked at the feeding sample plan which said to feed an adult mouse 24-30g every 7 days. I can't seem to find mice that big at any store.They are all weighing in between 15 and 20g. Can I feed two mice with a total weight between 24-30g? Would I put them in at the same time? or should I try to order a larger size in a larger quantity online.(will frozen mice keep?)