I wanted to sheet 2 old solid wood doors with 1" X 6" T&G pre-finished cedar
because the doors have sagged over the years & have numerous coats of paint
which I don't want to remove. But this will leave me with very thick, 3" &
heavy doors. So I thought about building a mortise & tenon frame & sheeting
that, but it's still going to make it thick & it could twist as dimensional
lumber isn't that dry. So I thought , what about a sheet of 1/2" ply with
the T&G attached to both side?

Don't think I 'I've heard of this before, so I'm wondering what the
drawbacks might be? Shouldn't sag too fast, shouldn't twist.
Any thoughts ?

Thx,
Chris