[ShadowChemosh]

The way I was going to go with a Pathfinder Gestalt addon was similar to how I implemented the play test for Mythic characters. You have the player add "three" characters. One is your Wizard, one is your Cleric, and one is a "gestalt" class. The gestalt class lets you pick your two classes for "level 1" it then figures out your saves, skills, and hit points and assigns it to itself. It then takes the wizard class and cleric levels and takes them out of the leveling process. You end up with a Level 1 character with three classes but two of them are only used for their "Class Specials" and the "Gestalt" class is used for Skills, HP, BAB, Caster Level, and saves.

At level "2" you add two more class levels of say wizard/cleric but could be other classes. And on the Gestalt class tab you would have a class special to pick the level two classes. As we are taking the two classes out of the leveling process we should have no problem supporting characters up to level 20. The gestalt class just has 20 class specials allowing for picking two classes that are combine together.

Granted its not "perfect" but it will allow you to easily combine any two classes and it will support two caster classes.

Obviously its allot of work and I have not even finished it in Pathfinder (other than theory) but that was my "idea" to fix the issue.