I have to second the get your own laptop.
The company I work for has software that does hardware / software inventory regularly. So additional hardware added can and will show up.
Also, when hired we are told in in uncertain terms that tampering with the laptop can and will be grounds for termination.
Booting off of an external drive is ill advised as many work laptops have restrictions to the USB/thunderbolt ports as well as modifying bios settings.
Lastly, using corporate hardware (be it a cell phone, or a laptop) should never be used for personal use. It's a good way to lose your job. I know more than one person in my career that lost their job either from texts sent from a work cell phone, or using their work computer for personal things. It's just not worth it.
Plus Apparat w/ Soap&Skin is always a good listen