Indy, is there an easy, inexpensive way to do this?
I don't have AC on the laptop itself, so no patient data is on the internal drive, but if I wanted to encrypt, what would you suggest?
Inexpensive - yes
Easy - that is a relative term

for me (or you), I would say it is easy, it just takes a few steps and attention to detail.
If you think there is sufficient interest (or should be), I can spell it out.
I'll mention in passing that there are tools to encryption portions of your disk, but that misses the point of what most bad actors are targeting.
For those who target more affluent individuals/households, they are more interested in your browser and remote software than your patient data. A browser (or remote access) with saved passwords is like a master-key to all of your information and accounts. Scary. That is why I recommend an encryption tool like LastPass to vault your credentials.
I'll also mention that on the enterprise side we have been brought in to deal with patient data theft, and that is often done with something more sophisticated like a spear-phishing attack. Not typical of how solo-small group practices are breached.