So, I see this as an interesting case.

R7-T1:

Action: Choose an enemy ship at Range 1-2. If you are inside that ship's firing arc, you may acquire a target lock on that ship. Then, you may perform a free boost action.

PTL:

Once per round, after you perform an action, you may perform 1 free action shown in your action bar.

If you do any other action first (i.e. Focus) and as a second one (PTL based) you trigger the Action from R7-T1 do you get a stress token from PTL before performing free boost action (hence, you are not allowed) or after (hence you are allowed)?

If the Stress from PTL was assigned before the second action was taken then PTL couldn't work at all.

You cannot use PTL to trigger the R7T1 Action if it is the second action.

PTL only allows you to choose an action from your action bar.

You could take the R7T1 Action first, then focus (or whatever), or use Experimental Interface which works similarly to PTL, but allows you to take a second action from an equipped upgrade card with the Action header instead of an action from your action bar, then take a stress.

However in both cases, the Stress for the second action is added after all of the steps for the action have been completed - so the Stress does not interfere with the action.