Ok....Plan B is up to bat. Has anyone that built box blind steps used 2x6's for the main runners? I seen a Youtube with some guy making them but he didn't show the stairs installed so I don't know what the finished project looked like. I would use 16 footers and set vertical 4x4 posts on each side, top and bottom, to support them.
Plan C......get a 15' metal ladder stand and modify that to use as the stairs/ladder to the blind.
The owner wants something his 6 yr old kid can safely get up in the blind with so I have to consider that for the build. A handrail will likely make it the safest to use, especially when it's snow/iced over.
If ya have any pics of what ya did for stairs I'd appreciate it.