Good choice.
Actually the alternative desktops on top of a working Plasma (or maybe also the LXQt) iso installed should work fine.
Probably even better a Gnome iso.
I was just going to test the COSMIC desktop on the Plasma6 slim iso today, when some more urgent tasks stole me from the test
(we always get some more urgent things to look after… 
)
Will keep you informed and probably will make a post about.