Then it stopped working with Windows Server so there went that loophole
It's annoying when software compat breaks.
Why do you need windows server for this? RDP works on desktop windows, just with the limitation of "1 seat".
Also I was using an out of date version of Windows Server just to maintain MYOB functionality which in hindsight seems like a bit of a silly sausage thing to do.
Normally I'd say that's perfectly fine, just keep it isolated. Sadly that's not how you would use MYOB: you need to have bank statements open (in a web browser) and documents from various people in your company (in an office suite), not to mention ways of getting those documents (network shares or worse).
There are some virtualisation solutions that make the windows of apps in the guest appear as (individual) windows of apps in your host. It's been a while since I've read into it, but it will probably be much more convenient than the traditional VM-in-one-window approach. Especially when juggling multiple things.