Substitution - Advice Please

I had a UA last week and failed, luckily I get a retest. I really need this job and am not playing around this time now that I have more then a 12 hour notice of the test.

So I am going to do the Substitution from a friend I know is clean. There is one problem He lives about an hour away and my test is at a funky time.

Background: My clean donor can only give me the piss on Sunday so I have to preserve it Sunday night Monday at work until lunch when I go to take the test. So I will have to preserve it for 12-15 hours, how do I do this?
From what I have read you can refrigerate it for 72 hours but when I have to go to work I have to take it with me for about 3-4 hours then test.

So do I get the sample from the donor drop it in a cooler and cool it with ice until I get home and put it in the fridge, then take it out in the morning and place it under the crown jewels and let it slowly warm in my pants the next 3-4 hours until the test? I am guessing the slow warming idea would preserve the bacteria the best or is quick heating better?
I also have a baby thermometer the check temp and have test everything with water about 4 time and got the right temp the last 3 time (2 hour wait with each try)

I also found this info on preserving it and just wanted to what you take is on this and if its good info then enjoy.

Thanks
PuffPuffGive

You're going to have to have something to keep it warm aside from your junk. They check the temperature at the testing facility, and if it's not within the right temperature range, it's an automatic fail. Your crown jewels will not do the trick on keeping the temperature right. You might be able to keep it warm with one of those little hand warmers, and from what I've read, you might be able to get one at a sporting goods store.