Just tell him you want the accessories package that Triumph is subsidizing and you don't want to spend any more than 8000 out the door.
If he says no, then say maybe you need to wait another few months to see how the market goes. I bet he won't let you leave the showroom without the sale. Also don't let him use the accessories as a bargaining chip. They are not his call, they are Triumphs call so they are yours.
His new bikes are showing up in a few months. He needs to sell now. Keep you manor as though you are thinking maybe you don't want a bike after all. He will see you excitement as weakness like a shark and blood in the water.
I won't spend the time here to teach you floorplan but that bike at this time of year is probably costing him money just to sit there.