I really don't mean to sound dismissive or whatever here but...
As much as I love FC, why are you looking to reinvent the wheel?
If you want a 'classless' d20 it'd be far easier to use one of the existing systems instead of trying to hack up a series of modifications and house rules to make FC classless.
It's not my intent to reinvent the wheel, or to drastically change FC/MC - I "simply" (scare quotes!) want a single, highly-flexible 'generic/meta-class' (for lack of a better term): for the express purpose of better fitting my campaign setting. FC is
a 'toolkit' rpg after all.
Perhaps rather than thinking it as 'classless', maybe think of it terms of me creating my own campaign-unique Class - instead of calling this new Class 'Hero', I could call it... 'Guardmouse' (my campaign will be based on the Mouse Guard comics), and PCs in this campaign must all choose Guardmouse as their Class - so this new Class I'm creating needs to be rather loose/flexible.
I absolutely want to play MasterCraft/FantasyCraft, and not something else.
So before I say, "Nah, definitely too much of a radical change - ain't gonna work; I'll just adapt (and restrict some of) the default classes"... I'd like to at least make an effort and try.
Rather than calling it classless
, it's more strictly accurate to call it... idunno, mono-classed
(after consideration, I decided for now that I'm not
going to tackle the "PCs are generated using an adaptation of the NPC system" - so I just want to now focus on trying this mono-class idea)
Hope that at least makes a little sense, even if you still disagree that the concept is worth pursuing.