The demonstration of design dive speed essentially requires:
At the design cruise speed Vc/Mc and maximum cruise power, select a flight path 7.5 degrees lower and hold for 20 seconds. This is followed by a 1.5g pull out. At the commencement of the pull up a power reduction and use of speed brakes is permitted. The maximum speed reached is Vdf - demonstrated dive speed.
The speed increment would typically be 0.07M.
So your proposed method would be unlikely to exceed a speed which has been demonstrated during certification, and still has enough "fat" for a 1.5g pull. .
Of course you could take no action until the weight burn off reduced the stall speed sufficiently!!