To my knowledge, there’s no guarantee that TRU will ever get the set at your store, I’ve seen them carry large sets like that before, but it’s not common. I’d say more than likely they won’t ever have it.
I’ve also used TRU Rewards points, but you’re right, they expire quickly, and I hardly ever shop there anymore, so I never build up a large supply of points.
What may work for you is buying it online, I can’t remember the official Toys R Us website off the top of my head, but I’ve ordered from it before. You can use your rewards points there, and an order that large should qualify for free shipping. And if they don’t have the set on the website, you can be pretty darn certain it’s not gonna show up in a store either.