As others have said, it is not doable for at least 3 reasons:
First of all, the Tamron teleconverters are only compatible with the Tamron 150-600 lens, not yours. And the Nikon teleconverters are not compatible either, you cannot even physically mount them to your lens.
Secondly, a teleconverter wastes light as it only enlarges the center portion of the image and discards the rest, thus it reduces the aperture of your lens. Using a 2x TC with your 70-300 that is f/5.6 in the long end will become a 140-600mm lens and having a f/11 aperture at 600 mm. No autofocus in any DSLR on this planet works with f/11, so it will be manual focus only. Seeing through your f/11 lens with your eyes will be hard too, the small aperture makes the viewfinder very dim. So, not even reliable manual focusing, but mainly guesswork.
Thirdly, to add insult to injury, teleconverters magnify lens aberrations, like softness and CA, and thus it is recommended to stop the lens down a stop or two when using a TC. Stopping your now f/11 lens to f/16 to fight the aberrations and to regain some sharpness will require you to boost ISO quite a bit. Calculating quickly with the sunny-16 rule you'd need to go all the way to ISO 3200 in bright daylight to be able to hold at least 1/1600 sec shutter speed. And if you're trying to shoot something moving, then even higher shutter speeds (and ISO values) are needed.
Long reach with good image quality and reliable autofocus requires a different lens altogether.