Hi, Geoff. Kept seeing this thread title but wasn't sure if I could add anything useful... I probably can't but after listening perhaps there is a technique that might help you with this.
Do you own the Craig Anderton X1 Advanced Workshop vid? If so in the Next Level vid (the second one) at minute 00:48:20 there is a section entitled "Multiband Imaging For Mastering". In it he shows how to completely isolate/remove the bass in a mix using the LP64 Multiband (but the Sonitus would likely work too). He then makes it so that range of freqs are mono by turning the output of that isolated bass signal to mono thus totally centering it and getting it out of the way of everything else (IIRC he does this on the bus but I'd have to rewatch it). Of course since it has isolated you can do whatever processing you want on it without messing with the rest of the mix.
It's a cool technique and it seems to be what you are going after. You are using the Spectral Dynamics method, right? This is kind of a manual way to do that (I think) so perhaps by doing the "isolate, mono-ize, process, blend back into the mix" method you can sharpen up/draw out the bass without muddying everything else up... which seems to be what was happening in your first set of vids (I personally like the original best as well but could see how the bass player might want more low end oomph which could be achieved with the process I just described).
Anyhoo... you know I'm just learning but your vid and this convo made me think of that tutorial/technique so if you have the vid check it out and maybe you can figure out a way to do it with your Melda stuff or in conjunction with it.
The basic premise is to totally remove the bass from the mix (as in do not just isolate and then re-add the signal overtop of the old... you yank it and ONLY reintroduce the process mono version), mono-ize, process then blend back in. Considering how slick everything else sounded and you just want some extra low end meat that seems like a good way to good. You can also get the kick centered at the same time.
Cheers... and sorry if that isn't helpful or doesn't make sense. lol