Sales Tax

Hello, having a weird edge case situation on paying sales tax on new to me TT.

TL;DR Sales tax was charged on a casual sale of used TT from non business living trust to me. Tag office cites non existent laws that all trusts are entities thus all are business/dealers. I plan to appeal to GA DOR and or Tribunal as its ridiculous.

I am in GA. Trailer was sold to me by a living trust that for legal sake did not engage in any business nor held the TT for commercial reasons and it was stipulated on the BOS. The tag office has slapped me with a big sales tax(few thousand as its a quality TT) as trust = entity = dealer. Note this isnt TAVT but specifically  a sales tax on a trailer.

What im struggling with is that you cant just blanket call all trusts a "dealer" and skirt the whole casual sale exemption as for all intents and purposes thats what it was. Georgia law is very clear on its definition of a "dealer/business" and this is not it. I cant find any Georgia law that also blanket cover all "entities or trusts" as dealers. Only thing I see that sales tax only applies if the sale of tangible property was done by an entity engaged in business which this living trust isnt. 

I wanted to post here to see if people ever tried to appeal similar or exact situation because this situation simply ludicrous. If folks are experienced with GA law ill take specific statutes that either support or take apart my case.