Even if Holdo wasn’t name dropped, perhaps we could see a few ships manage to escape the Hosnian destruction by jumping to hyperspace at the last moment. I’m pretty sure someone did this in their edit. They added a Holdo close up but that wouldn’t be necessary.
And yeah, I think the idea tracks in your mock up, but I’ve seen it so much I may be biased. Though Rey wouldn’t necessarily have any idea the map might be in R2, so she would just be fixing R2 without realizing what is in him. So I can see that being an advantage of adding 3PO to that scene. Still think it would be worth a mock up even if you waited to mess with any effects.
Absolutely love this idea! Seeing a couple hyperspace jumps right before Starkiller destroys the Senate would really help tie into TLJ as to where the bombing fleet came from