The SoD guide for SIV on the Suikosource website mentions that Pecola can be recruited directly after recruiting Warlock providing you have spoken to the lady on the main square of Middleport who gave you her book, after what Pecola appears in Warlock's former house. I tried to do it and was tearing my hair apart because Pecola was never appearing in the house. It seems actually that you specifically need to come back to Middleport by entering the ship in the harbour rather than teleporting with Viki. I googled it and several people could only recruit Pecola this way. Only after I did it this way was I able to recruit Pecola. It's kind of stupid but it seems true. I suggest perhaps you mention that in the SoD guide? Something like Warning: you have to enter your ship in the harbour for Pecola to appear.
This is true for several SoD, at least it's speculated. I think I never had any issues with Pecola.
There are actually some SoDs that are hard to get, I think Ugetsu doesn't appear if you don't have enough recruits (something which is rarely the case, but I noticed it during a no-recruit run. Which is btw impossible because you always need recruits at some points in the story).