My only concern would be the packaging of your 15 meter throw rope. It is too likely to tangle when deployed as you presently have it packaged. I would prefer an appropriately sized nylon bag into which the line is stuffed with one end just outside the bag. When needed, you hold that end and throw the bag. It works flawlessly. You might not even need the lead weight (experimentation is recommended).

A place that sells sea kayaking gear will have items like this, but the commercial versions that I am aware of are all bulkier than what you need.