In case anyone is/was in my situation I'll follow up with how it went. I used a nonlubbed condom and twisted it and secured it with a bread tie. I pinned it to the inside of my briefs and placed a hand warmer on top... Drove to the place parked a little distance away and took the temp, it was 96.7 degrees and I saw someone waiting in the waiting room. So I drove 2 blacks away to a burger king, grabbed a hot coffee and took it right in the bathroom to get the clean urine hotter. I heated it to 103.5 degrees then drove back to the place. I was in and out in under 10mins, went perfectly because I practiced!

Thanks n2 and burnttoaste!