This chat also reminds me about a converation I had with Jay once when we were hanging out... about the order of things. I always theorized that the idea for Wacky Ads came first, since the post-card format & art style & more cheezy gag style matched earlier parodies out there. Plus they weren't Saunders. And Jay mentinoed a few things in talking about them which seemed to point to that being the case. But then the idea may have been shelved until the 1967 die-cuts came out (with a more traditional trading-card size) or maybe they were creating both at the same time & chose the smaller cards to start with. I remember this being a big discussion point in the older John Mann forum at one point, but it was never finalized. If this was the case, it might give another explanation for the unpublished titles... like that they didn't replace #25 G&E, but instead were replaced BY the multi-title panels of 1967 die-cuts, as a last minute substitution to relate back to the 1967 release for continuity.
This may also leave room for 4 more unpublished titles (since there are six multi-titles), including 2nd series sticker titles which did not appear in the Wacky Ads (which could include, LogCave-in, GyppyPop, Putrid, 8Lives, Brittle, Dull, and RunTony... although probably not Sugarmess, because the crappy puzzle titles like this often seem like last-minute throw-together pieces). Imagine if an unpublished Wacky-Ad version of something like Guppy Pop ever surfaced!