Bhibb Any pitfalls I should be aware of? Words of warning like "stop trying to have it all"?
On my main laptop I have 5 different Solus DEs, an installation of Sparky Linux, Windows 10, and more, but it's all done with virtual machins (except for Solus Plasma). That would be the preferable way to accomplish what you're asking for. Your KDE and GNOME machines would be secure in their own areas, with no chance of interfering with one another.
Yes, you can have it all, and with no conflicts. Take a look at virt-manager or gnome-boxes in the repository. If your needs are modest, either of those should work fine for you, and they're easy to set up and use. If you find that you need something more robust, VirtualBox is also available there. It has slightly more of a learning curve, but it's still very easy to learn and use. (By the way, this is virtualbox-current in the repo unless you're using the LTS kernel, then it's just virtualbox.)
And the nice thing about all of these is that if you're not happy with a VM you've created, it's easy to delete it, get back whatever resources it used (e.g., disk space) and create another.
