I use a product called temperature alert.
http://www.temperaturealert.com
They have a USB device that is about the size of a USB flash drive. I have a small laptop I leave in the RV and I use either my cell phone or my wife's cell phone as a hotspot (or use RV parks WIFI if available). I have the software set to email me the RV temperature every 10 minutes. When we leave the pets in the RV, I will just check my email several times and I can see the temperature inside the RV. If I do have to use one of our phones as a hotspot, I just forward the phone that is left in the RV to the other phone in case a call comes in (very easy if you have a iPhone). We use the other phone to look at the emails. We usually don't venture too far away so if I notice the temperature rising, I can head back to the RV.
Burch
