With a GR1 especially that's overkill on the wrapping. Wrap few good layers paying attention to the corners and your good. Some do six as a stack like this:
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personally do four in a stack, then lay the stack left to right, add a top and bottom

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Strap tight inside and there will be some gapage at the bottom. I've a light yoga block in that gap to protect my back a bit.

Add low crawling, bear crawls and crab walks to your training. Pack must never touch the ground in a GRC. Also, learn to carry logs, rocks whatever you can find on your rucking. As you will be doing that in the GRC. They are a blast