L-C-R incorporates mono into its very core. Just pan things C. If “the stuck placement of everything” bothers you, then look elsewhere than L-C-R. Go back to regular stereo, panning things where you like. It’s just a concept, that could either help or hinder. 
Love stereo micing of an acoustic source/space too, matched pair of KM84s here, into TG2 pre, it’s unrivalled, IMHO. That fits L-C-R too, just pan the two mics L-L, or L-C, or C-C, or C-R, or R-R. The only thing you are NOT allowed to do is pan things “between” the L, C or R. But again, it’s just a thought experiment. If it doesn’t work empirically, then try something else.
I have to be honest and say that I’m not really a fan of mono mixes, and usually prefer the stereo mix, given everything else is equal. I grew up listening to my dad’s collection of Beatles mono vinyl, and I still prefer the 2006 stereo digital remasters.
For great Jazz recordings in stereo, check any of Rudy Van Gelder’s recordings/mixes, especially the Bossa stuff, an absolute master, and took his techniques to the grave with him…