As much as I hate showing anyone this it was a project that was only meant to last 6 months. Just enough time after I shut down my contracting business to sell the house and leave cali........that was 5 years ago now LOL.
SO the original intent was to use two 40's on either side just like what you plan on doing. The day I was going to pour the footings I found out code enforcement outlawed these things and were cracking down. So I backed off on using one for the right side and painted the other camo green........stealth huh
I ordered a 100mph wind rated RV cover and attached the base plate upright support to the side of the upper rail of the container with 1/2" bolts every 5ft, basically at each truss receiver, the second picture basically shows it (you'll see a small hole). The inside of the container thru bolt is backed up by a 90 degree unitstrut bracket that supports deep strut spanning the width (obviously every 5ft). This allowed me to run/support conduit and hang my lighting from so once again no roof penetrations. Then I used 6 X 6 flashing at the transition under the roofing metal and to the top of the container sealed with mastic so no mechanical attachment means on the container thru the top. So far no leaks.