Sintra in the 6 mm Thickness is very flexible, certainly more than sufficient to bend around any Stairwell short of a Circular Stairs.
I've carried many such a sheet, even full 5' x 10' ers down stairs that had normal sized center landings.
In your case, doing a 110" Zero Edge affair, the 5x10'er would be cut to 96" x 54", and that certainly ain't all that big. It will easily go down the stairs upright at a angle, and make the landing turn easily.
Things to consider:
- You are NOT gonna crack or break the Sintra
- It's much easier to work with, as it will adhere to a Wood Frame using PowerGrab Adhesive (clear)
- I suggest a Frame made from an exterior Ring of double 1x3, the outside on edge and the inside flat and flush to the face. (See Example below)
- The 1x Lumber will be both lighter and easier to accommodate the LED Wiring "Pass Through"
- The 2.5" stand-off will allow you to use a standard 110 Outlet behind the screen as well as contain the needed Cord / Transformer assembly
- Hanging the Screen will be easily accommodated by using the "French Cleat" method, with the Top Horizontal made from a ripped 1 x 6
It (..the Frame...) will go together easily, and while a bit more work than just some 2x4s, it will be rigid, lightweight, and easily hung.
You can certainly paint the Sintra elsewhere, the small amount of flexing will not hurt it. I would suggest using some new, inexpensive Cotton Gurnsey Garden Gloves while moving it. (...and after it is thoroughly dried...) As you negotiate the Corners going down the stairs, just be certain to keep the Painted side on the outside of the bend to avoid contacting the inside edge of the Stairwell Bannister / Framed Wall.
Lastly, lay down a clean, soft Cotton Sheet and place the painted Sintra "Screen Side" down. Mark off the 1" inside perimeter and glue the Frame on the Back