Elevated dog bed size Questions

Anybody out there with a GSP have an elevated dog bed from a company like Kuranda or K9 ballistics? I have a 6 month old male and having a tough time estimating what size he will need when he is older (est 60 lbs per his parents sizes) as I only want to buy once (expensive). If you have a grown GSP around 60 lbs and have a raised bed, curious what size you have or would recommend to others. Thank you.