Van life with a toddler

Hi! My partner and I are currently in the process of making adjustments to our van to accommodate our toddler on our next trip. We have a long wheel base sprinter with a fixed high bed at the back. Currently wondering about sleeping options for our 15 month old? We want to keep him out of our bed if we can help it! I've had a look at some cab beds but just worried he'd be able to climb out. Has anyone here got any tips for travelling long term with a toddler, and what were your sleeping arrangements?