I know it's best to go with characters that fit the gag but if you're not even spoofing products with sex appeal then it's hard to arrive at a character like Umbrella or IOU. Some of these Wacky series are supposed to be geared for adults like the postcards and Old School. Shouldn't you then write gags that actually appeal to adults? I'm not a child. It's not like my sense of humor was stunted at age 10. The postcards and Old School look like they're for children. That makes little sense to me.
R Crumb in particular had a keen interest in exploring the possibilities of rendering the female form in cartoons back in the day when he and Lynch were the vangaurd of the underground comix scene. Norm's pulp magazine covers also illustrated his eye for buxom women, which managed to slip into a couple Wackys. I do think there is a place for some big boobed female Wacky characters, but it is a fine line. For one, these were marketed to 10 yr olds, and we love them not because we still have the sense of humor of a 10 yr old, but we remember ourselves at that age and it provides a way back machine to that ideal joyful fascination and perspective.
There is a difference between childish and child-like, with the latter having the connotation of idealism and innocence, which is always welcome when things get darker and more cynical later in life. Not full tilt regression, which may require psychiatirc assistance;) But I do think it is advantageous to retain those elements which made Wackys what they were and Old School does manage to do this. Since the ANS and Flashback had only moderate success, it is fair to say the Wacky market is dominated by 40 somethings. To change the formula very much from the original intent, which combined both an adult irreverence and appeal to adolscent humor, would break the mold. That being said, bring on the big boobed Wackies.