The thing with Mature is that you can "technically" develop a rushdown technique that looks continuous, but there will always be holes in it no matter what. The object more or less is to cover those holes up or constantly switch them up, so that the opponent can't truly tell when to strike back with a reversal.
You already know the tools to use: rekkas, qcb+B, cr.B, cl.B, s.B, sometimes far s.C, cr.A, s.A to name a few. You have to develop your style or rushing down, while putting fear into the opponent, so he/she won't attempt to reversal, GCCD, or GCAB.
When you conceal these holes within your rushdown, keep in mind that you can start developing good reads on when your opponent attacks, as you can use Heaven's Gate to beat out whatever they attempt. While that's not a necessity, it's something to think about - it was more needed in the older KOFs imo, but she doesn't need that, because she can punish pretty well, especially with HD combos and EX combos that can go into HD if desired.
Speaking of combos, I might have mentioned this before, but it's because it's essential- master her cl.C to EX Metal Massacre link. I kid you not, with a couple of bars, you can simply do that loop twice, and link that with a cl.C and go into HD if you like, or just finish with rekkas or whatever. It does a huge chunk of damage, and you don't have to spend drive if you don't want to. Personally, depending on amount of life left, I'd spend it, only because she is capable of building whatever meter she used.
Yeah, I wouldn't worry too much about zoning with her. Again she's no Kensou, but whenever you do need it, it's there. At the very least, it allows you to close in without doing too much, per sé. But the thing with that is you have to read your opponent and see what they do. If they roll, then you've got good options, starting with a throw at the minimum. If they just sit there and wait to jump, you use Despair, cr.C, or even a s.C if timed right, which becomes cl.C. Essentially, you're not zoning to keep away, you're zoning with the intent of closing in.