I get agro when cooking hemp at home from the wife because of the smell, so now what I do is using an old flask that I have.
On the morning that I go fishing, I put the hemp I need for a days fishing in it (not more then half full to allow for the hemp to swell up). Then top up with boiling water and close the top.
When you get to the bank side (I norm take about 1-1.5 hours to get there after filling the flask), empty the hemp in to a bait bucket and let it cool down. Its then ready by the time you have setup.