Home Forums Gear Photography Lens for Africa

I have a Nikon D7000, which currently had a Tamron 18-270mm f/3.5-6.3 Di II VC LD.
This is a neat lens, though sometimes I can see it lacking speed in less than ideally illuminated areas (indoors), and on very long zoomed in pics.
i am planning a trip to Africa next year, and though it is a great excuse to get a different lens.

One similar lens is the Nikon AF-S DX NIKKOR 18-300mm f/3.5-6.3G ED
but I don't seem to gain much with the aperture range, and then going to separate lenses such as
Nikon AF-S DX NIKKOR 17-55mm f/2.8G
and a 55-330, but now it implies changing lenses, and ramping up the money.

So, anyone experienced in wildlife photography, should I keep the Tamron and run it, and just get a smaller lens more suited for indoors? (which seems like the best idea)

Thanks