Not that they are trying to shut you down per say, more like remembering the practical reasons why you won't see "small batches" produced as its been a long haul for the taillight repo and they still not a "complete unit". Tool and die in means of manufacturing is a costly game and furthermore these "small batches" would be more cost then the demand would pay for. And not to mention the liability insurance and other over head for a big company hit or miss, small company perhaps more feasible if had the proper permissions and rights to be able to do so. Now small local "custom" shop or person even can produce your desired product. Lots of skilled professionals and local to you even that can produce your needs. Question then is are you willing to pay. Again someone has to pay to produce. Always someone to step up if there's someone willing to pay.
I used xj filler hose, and some instock rubber hose for vent.