OK I know you were looking for STM advice... but I'm just sharing my sister's experience...
They have two little boys 13 months apart - Their home had a master on the main level and 3 bedrooms upstairs. They kept the baby in the PNP Basinet downstairs until he was about 3 months then moved him up to the crib in the upstairs bedroom. When LO#2 came - LO#2 was in the PNP downstairs until 3 months. They put LO#2 in the crib and put LO#1 in a toddler bed (at about 16 months).
Maybe if you are super worried about LO moving around, get a video monitor for her room just so you can see what she is up to from across the house...