Here is what I got so far. I added 4 unistrut cross members. I'm finding that I had to cut off all the springs for the unistrut spring bolts or else the spring easily gets caught in all the holes in the channel.I originally had each rail/cross members junction with 2 bolt 90 degree connectors but the cross members like to twist under load so I replaced all the connection points with 4 bolt 90s. I also added elevator bolts through the plywood bed platform to the unistrut at all corners and an the edges so the platform doesn't slide around. I cut cardboard templates to make the lower panels and scribed them into 1/2 hardwood plywood. So pretty darn strong now, very little deflection. If I had to take the bed out, it will be a bigger deal than I'd like but I'd rather be safe than sorry. I know I will have to rebuild things as I use the van and things don't work out like I thought they would, but this will keep me going. I really like Bills idea of long storage under a torsion box.