Ds is 8 months and still wakes regularly, he is in a cot bed with one side removed pushed against our bed in a type of co sleep arrangement. Problem is I have had to lower the mattress as he is pulling himself up on the sides and nearly over the top, this means the mattreses are no longer level. As a very short term meaure we have books under the legs but it is not ideal and still not quite level. How else can I get the beds level without risking him climbing out ?