This is what I have done, I am NOT advising you in any way, take it as an example.
I have 3 cartridges that I use for hunting and also for comp in DIFFERENT rifles.
I couldn't decide on just ONE, so I built 3 of each for comp, and bought factory rifles for hunting. I have used more cartridges than these for comp work, but that's a different story.
They are 6.5x47, 264WM and 300WM. The latter 2 are in Win Model 70 EW's and the 6.5x47 is on a switch barrel Rem 700 VSSF II for hunting, all have 26" barrels.
The 6.5x47 is used for different hunting than the other 2, primarily long range bunny, fox, goat and pig work. The others are used for either long range deer, goats and pigs, or just general still hunting or stalking.
I also use switch barrel setups on my comp guns and a few hunting rifles, I don't often change calibres/cartridges while hunting, BUT, if you want flexibility with ONE RIFLE, this is another way you can go.
Cheers.