Gosh, surprised you haven't been chastised for shopping at the likes
of Costco! Really been feeling the love as the term 'white trash' has
been circulating wildly throughout this group. : )

But in answer to your question, freezing your rice in ziploc bags
would be your best bet. It could end up damp once it is thawed,
however, so I'd use small enough bags that you would use it all in one
fell swoop. Or perhaps freeze a variety of sizes so you have options.