At this point your best bet would be to sub. I've used a 2oz dial bottle that was about 1/2" X 2". As far as the temp goes bring some hot water with you in a thermos, and a thermometer. Heat it to about 101 -102 in your car. I used an ace bandage to fix it to my thigh. I'd rather have it a little warm when I made the deposit. You can always swish it around in the cup to drop it to 1 or 2 degrees below body temp. Its worked for me in the past... It should also work for you.

BTW, you could also use a condom(no lube or talc), but I have no personal experience with that method.
The condom method is explained in detail on this site

Good luck