Question: Caravan Interior

We have bought a new 21 foot Newlands Zodiac family van - 3 bunks. We have got 2 children one of them is a baby (8 months). The first (and last time) we used the van, the baby was so tiny that we just installed some hooks and a sailing saftey net on the middle bunk but now he is full mobile, crawling and standing. We are so confused what the safest and easiest option we can do to keep him safe at night. He still wakes during the night so definitely need something I can get in and out of easily. We are so sure that there is something but continue to argue about what we can do. Has anyone transformed a bunk into a safe place for a baby? Happy to get any ideas!!!! The van is to small for a portacot!!! Help me....need to get this sorted before our 3 week Christmas trip!!!