Hi,
Unless you're using a really old version of HikaShop, or the code in your show_default comes from a really old version of HikaShop, or is heavily customized, you should have that code.
Because of this, since I don't know the code you have in your show_default, I not sure what to tell you since the location I would tell you would still be based on the show_default default code of HikaShop 4 and not based on your show_default.
But let's try a second time.
You could place the code after the code:
$this->setLayout('show_block_characteristic');
echo $this->loadTemplate();
Since you said that you want the new view file displayed after the characteristics, I suppose that you should have that code in your show_default, since that's the code to display the block for the characteristics.