This is pure speculation as im only just a beginner, but heres my two cents
Could you not make somthing where when you trigger a custom event (shooting the platform) it toggles “simulate physics”, you apply the impulse and then toggle the simulate off again, you could use delay nodes to help with this, i think if you used a sequence node you could trigger the physics and impulse almost simultaneously and with a brief delay after the physics toggle, toggle it back on to regain control
like i said im a total beginner, is there any logic to this? xP