Hold your horses. This crisis did not rear its head this morning.
First of all - hear say is nothing you can rely on. No official rule? Read the rules for your C1/D. Read the rules for VWP. You are intentionally planning to violate them. You have to consider purpose not only number of days of stays.
Unless you are working you cannot use your C1/D priviliges through immigration. Either immigration or your airline will catch on pretty soon. How long you can stretch this? It is a gamble. How will a secondary interview or even a refusal of entry affect your work status? HR will be able to answer this.