Good morning, Ed.

If you can't put up a beam, then I'd say that your multiband folded
dipole and a multiband vertical will give you very good performance.
Since you already have the double bazooka antenna, stringing it NW/SE
as you suggest would give you another option, but I wouldn't go out
and buy one if you didn't already have it.

The folded dipole 6 feet above the top of the concrete wall might give
you good NVIS coverage depending on the action of the rebar in the
concrete (not sure about that).

73

Rick WA1RKT