If I have a Fighter 5/Rogue 2 (so I have both Extra Attack and Cunning Action) am I able to shoot an enemy with a bow, move to cover, bonus action Hide from Cunning Action, and finally make my second attack from Extra Attack?
The rules on bonus actions state:
You choose when to take a bonus action during your turn, unless the bonus action’s timing is specified, […]
However, I'm not sure if that means I can take the bonus action in the middle of another action. I can see it meaning that you can do this, but I can also see it meaning that you can take it before or after your action and/or movement.
I know you can move between the attacks, but that is something that is specifically spelled out, which is another thing making me think this might not work the way I want it to.
Yes, you can use a bonus action then
You answered your own question :) That ruling on bonus action states that you choose when to use your bonus action unless that bonus action has other riders (like GWM allowing another attack if crit or reducing the enemy to 0 HP...meaning you can't take that bonus attack until that circumstance occurs.)
You are completely free to take your bonus action Hide at any point in your turn.
(However, you will still need to make the stealth check to hide - which may be at a penalty since the target may have seen you go to cover after striking.)