Oh really now? Even if it doesn't work, I'd be interested in hearing the theory for this.
There's not much theory, really. It was more of an assumption that clearing WB Forest requires a boost above 2.5 on a rainbow team, since that's what LL/G3, Rayleigh, WB, etc, provide. Iva's one of the only other ways to get that, so I wanted to see if it was possible. I can't remember if I ultimately decided on Iva/Iva or Iva/Rayleigh, or what the crew members were. My saved team on github is Iva, Iva, Mihawk, Perona, GP, and Broggy, but I don't think that was the final group. Can't remember why I'd put Broggy there over any other INT character. I believe I was trying to "replace" SWS Zoro with either a damage reducer or a healer. Anyway, I'll put more thought into it later today, but like I said, it might be a complete bust. Iva does get a boost against WB himself, at least.
(The other thing my theory was based on was the assumption that Bamco wouldn't introduce content that was absolutely impossible for F2P players, which is probably an optimistic assumption. Hawk Forest is doable for F2P though, so maybe!)