I came across this company a while back;
They make "care beds" for adults and children with special needs, which are really just very large cots. They offer models with locks on the opening side, plexiglass coverings on the sides to stop you reaching between the bars (and by extension, getting access to the locks on the opening side);
And bars on the top to stop you climbing out;
And they make them in bright colours too! I remembered them as I thought between the colours, the designs and all of the options they inadvertently make what is quite possibly the perfect AB cot!
Hope that helps