Accidents happen, and not being able to destroy blocks in the trader area can be frustrating.
It is no secret by now that activating a quest from a trader will reset the chunk for the targeted prefab. This logic could be applied to fix issues in the invincible trader area.
Have the trader always have a quest ( Or an additional chat option ) That starts a quest at the entrance of the trader, similar to other quests. Have it be completed by talking to the trader, just how the 'White River Citizen 1 - Journey to Settlement' quest is completed.
My particular issue
I have built a base near the trader for the first time, and my bird's nest tower fell over due to a lack of support, landing in the road that is dividing my house from the trader. I simply want the debris to go away, but can not due to the invincibility of the area.