fore-aft testing in vertical orientation

The aceelerometer is mounted on top of the vertical wall of the rigid fixture while the DUT is on the horizontal plate of this fixture. The
DUT is an assembly of a light Al stmamping (1.25 mm thick) riveted
(3 rivets) to Mag. casting (part of the whole assembly).


The DUT can only be placed in vertical orientation where as the real
world orientation is fore-aft.

1) Is it realistic to put fore-aft loads in vertical orientation?
2) There is no accelerometer to check output on the DUT which is about a
feet off of the control accel.
3) Unforeseen failures on the rivet heads has been raising suspicions
on testing method. (I am not an expert).