Hi Tellstar , Welcome to UKCS , you could make them quite easily from some plywood , i replaced 9 in my caravan , just cut to size , then glue and staple in place .
Hello, it's your lucky day! I have 8 bed slats that I don't want as we're moving house. They came out of my old Esprite and they're very strong (don't ask me what wood they're made from but having done my own repairs in the past they're stronger than plywood). They measure 760mm long x 45mm wide x 16mm thick. I was going to put them on Ebay but it's just not worth it. They're yours for free if you can figure out a way of getting them from me to you.