There are no restrictions for the method of eliminating the peggies. You are not locked into using only a Bow.I'm 67 and maybe thats why i could never learn how to use the bow in FC4. I never completed the game because you have to complete missions using only the bow. PLease, does FC5 have missions you have to complete using only the bow?
However, If I might suggest an easier way to use the Bow in FC5, you might find that it is enjoyable even ?
Like yourself, I don't have the motor controls of the young people at our ages, we lose some of that reflex naturally so when I use the Bow ( any bow ), I turn Aim assist On and I add the perk that allows for faster loading and aiming Bows and Slingshots.
Then when I want to take a target out from 180 Meters, I choose the Tactical Sight ( the one with Numbered Lines ).
While Aim Assist is on, I scope / Hold Breath / Draw and Release. Aim Assist will put the target at the correct distance for a body shot and most times will be a one shot kill.
To be successful, you need to scope and hold breath in quick succession ( something we can still do at our age and the Aim Assist will do the rest for you.
Erm... this assumes your on console, I don't know if PC has the option.