Generally speaking, true telephoto lenses have their own tripod mounting ring so that the lens itself is attached to a quick release plate and directly to the tripod. The center of gravity when a camera is attached should ultimately land near the point where the lens attaches to the tripod.
This is a specific aspect of lens design in that it allows larger lenses like telephoto and supertelephoto lenses to be used with a gymbal type tripod head. These types of heads are designed to allow automatic gravity centering of the mounted lens and camera, while also allowing quick and fluid tilt and panning. They would never work if the whole unit's center of gravity were off, say at the camera or near the lens hood.
A camera with a battery grip might offset balance a bit vs. a camera without, but in the grand scheme of things a battery grip and an extra battery tends to weigh a fraction of what a supertelephoto lens does, and is even only a fraction of the weight of the camera body itself. With a gymbal mount, you might experience a slight tilt towards the back of the lens/camera, but it shouldn't be significant.
Speaking about your specific lens and camera combination, the addition of a battery grip should be entirely a non-issue. That lens may seem long, but its tiny vs. something like the 100-400, and nearly microscopic compared to a supertelephoto lens like a 500mm or 600mm f/4. You should be able to hold the whole setup in-hand, rest the lens hood on an edge of a window and the like for balance, or mount the camera on a tripod with the lens hanging off the end without much problem. There will be some extra torque if you mount the camer+lens on a tripod with the release plate attached to the camera, so you'll want to make sure you have a grip on the lens when loosening a ball head and the like.