Alzrius
The EN World kitten
This reminds me of a post that game designer Owen K. C. Stephens made over on his Patreon page for what he calls "minor gestalts." It's essentially the same as the normal gestalt rules, but you can only gestalt with an NPC class.I expect to do that in my next campaign too. In my current Brotherhood of Rangers game, all the PCs have at least 6+Int per level because they're all ranger-gestalts. This also fixes the issue of those 2+Int classes having such short class-skill lists. Overall, this works for the Brotherhood of Rangers game, but it isn't a general solution.
In practice, this means having your gestalt class be either the warrior (for the BAB and HD upgrade), adept (for spellcasting), or expert (for the skills). It essentially lets you patch up an area where your standard class is weak, without getting all of the class features that a PC-class gestalt would give you.