Advice for a secure RDP connection

Hi all

This is in between home networking and enterprise, so I hope you dont mind the post
I have a RDP connection for my home PC
I often use it while im at work to connect in to home to test things externally (im a jr sys admin)
However I know that having RDP open is a bad idea,
I have it set to a different port, but even then I know its not secure

Iv been meaning to setup a VPN to remove most of the port forwarding I have on my router, but im looking for a way to best setup the VPN for my RDP

I can't make a VPN at work, as I still need to be able to connect to work servers etc.
and sometimes im using a different PC than my usual one (On the road with no laptop, so using someone else's PC)

Ideally im looking for some sort of RDP client, that uses a VPN
My backup plan was a portable virtualbox with a pre-configured OS with vpn, but I know thats doubling up resources and id like to try avoid having to run a whole OS just for RDP

Any ideas or input would be great
Thanks