I built this little set up in order to put a twin mattress (not pictured) in my bed with my gear out of the way. A twin mattress happens to fit perfectly side to side and front to back. I welded the T bars and bolted them into the bed.

 

nice, that gives me ideas for my rig... hmmmm...

 

looks like it leans inwards though...have you thought about moving the legs out for supports? Or would that interfere with your mattress?

 

actually it does lean on the end toward the bed. It is secured to the canopy with brackets that keep it solid. The leaning is my poor measuring on the back T bar. It is rock solid no movement at all so I dont worry about it moving. The little lip on the platform keeps junk from sliding off.

 

Slick Trick!!!
Is it pretty stable?

 

actually it does lean on the end toward the bed. It is secured to the canopy with brackets that keep it solid. The leaning is my poor measuring on the back T bar. It is rock solid no movement at all so I dont worry about it moving. The little lip on the platform keeps junk from sliding off.
Here are two more pics. The bigger cut is for the softopper frame.
I had limited space in the bed and as a result I had to put the T bars right along the lip flush with the wheel well. I got tired of sleeping back there on a mattress pad so I bought a mattress that would fit in there and man, it is comfy!
SOrry about the bad pictures but I have to do a remodel in the morning and all my crap is in the truck bed.