FYI heat pads for humans have a safety feature that shut off the heat pad after a few hours. That would be a real pain to keep turning back on, not too mention they burn humans.

If you have reptile heat pads bring one and buy a lamp dimmer from a home improvement store. They are roughly $10 and well worth the money, I use them as back ups in case my thermostats fail.

As for traveling use the insulated box and tape a heat pack to the top.

Simple