I don't see anywhere in the Collision Regulations that stipulates that the lights have to be at deck level when under power. Rule 23 refers:
There may be local rules or inland rules, but the International ColRegs normally trump everything but Inland rules, or every vessel would have to have different light setup for different countries.
There is a tide in the affairs of men,
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
Shakespeare, Julius Caesar IV, iii, 217