Could German auxiliary raiders still get to sea?

What stops Germany using auxiliary raiders instead of warships?

They must still cross the same watched barriers, and suspicious merchant-ship behaviour is more likely to be investigated.

Disguising a raider as a merchant ship does not solve the geographic problem. A ship moving alone, emitting the wrong signals, or behaving unexpectedly in a closely watched North Sea attracts investigation. Norwegian observers and Britain-Norway patrol traffic make the same narrow exit routes dangerous regardless of a vessel's outward appearance. The scenario's dense patrol and convoy environment therefore constrains auxiliary raiders as well as conventional naval forces.