For noise and all around use, I'd build 21 if I wanted a short carbine and 22-23 for tad better speed and getting blast that much further away from the ears.
That said, for you, I'd sell the Tikka and get the Ruger Compact. Nothing to keep you from putting a ball of rolled up tissue or foam plugs in to cut that blast from any rifle from ringing your ears. It will handle great.
I had a custom Model 7 built in 7mm BR, 21" .700 at muzzle and I never wanted to change anything about it, worked beautifully for me.
Your hunting ranges are short and the small diff in speeds won't affect your outcomes, but the blast is a concern, though it's a trade off for ease of handling. Many guys using XPs w/14.5" IIRC and get great results. Just know up front the blast will be greater as you know to expect.
FWIW I have a bbl on order and it will be 22-23" fluted varmint but I don't plan to climb up trees w/it - it will be a 260 or the 6.5x47 Lapua. I cannot imagine anything handier up a climber though then that Compact. You can always sell or trade it if you don't like it. A thought.
