Platform for the bed is pretty simple. I had square aluminum tubes cut to length and secured them to 2x4 runners on each exterior wall. I then used 1x4 lumber to finish off the platform. The deflection in the aluminum tubes is 1/2" and is a bit to much for my back. I added two support post that can be swung out of the way when needed. Perfect... I ended up buying two queen memory foam mattress toppers ($129 each) and just stacked them, cheaper than another mattress and has very good support.
The platform is larger in width than my queen mattress. I used 1x there to build additional storage. I will have several storage compartments here and will build a top as well.