@JASpup :-
I suspect you're not going to have much luck with MATE.
That in itself isn't surprising. Pup's first & foremost a lightweight, hobbyist distro. It's not a mainstream OS, and the projects all go out of their way, primarily, to support the "big boys".
I also suspect you'll find that most Puppians are more than happy to stick with the default JWM/Rox-filer 'pinboard' combo. Not because alternatives aren't available - as we know, they are - but because although the standard setup takes a lot of learning your way around, once you've got a handle on it, it's SO much more configurable than 'standard' DEs. And I think you'll find that many users, also, simply aren't bothered about what their desktop looks like.....being more concerned with functionality.
I tried them all during my distro-hopping days; Gnome, LXDE, XFCE, MATE, KDE, Budgie, Enlightement, E38.....I didn't really like ANY of them (with perhaps the exception of KDE, but that was way too 'heavy' for the hardware I had then). Oh, sure; there are many far more 'polished', slick-looking DEs out there, but you're always kind of at the mercy of their developers/contributors.....you can't do much in the way of modifications yourself. "Customize", probably, yes; "modifying" the actual building-blocks themselves, no.
When it comes down to it, Puppy is basically controlled by a humungous bunch of scripts.....and scripts can always be edited/modified/altered to suit yourself. Every OS in existence has a text editor.....
Our Pup IS rather more 'hands-on' than most Linux distros. But I suspect that's part of what attracts folks to her in the first place, believe it or not.
It rather looks like we're back to the "if beginners can't do things easily, they'll go elsewhere" thing again, aren't we?
Mike.