The following porposal has been abandoned.
I've come up with the following feat tree. It has two branches (one con-minded and one str-minded). I also used the mechanic that is used in psionic feat (additional bonus with every feat along the tree). A dex-minded branch can also be added later.
Rage of the Jaguar
Prerequisites: Rage ability
You gain one extra use of your rage ability per day and all your rages last for three rounds longer.
Hide of the Boar
Prerequisites: Rage of the Jaguar, con 13, bab 3
Benefit: Everytime you enter rage, you gain an addition +2 bonus to your con score for the duration of that rage.
You gain one extra use of your rage ability per day and all your rages last for one round longer.
Anger of the Wolf
Prerequisites: Rage of the Jaguar, str 13, bab 3
Benefit: Everytime you enter rage, you gain an addition +2 bonus to your str score for the duration of that rage.
You gain one extra use of your rage ability per day and all your rages last for one round longer.
Heart of the Bear:
Prerequisites: Hide of the Boar, con 15, bab 5
Benefit: Everytime you enter rage, you gain the use of the diehard feat (even if you normally don't qualify for this feat) and Fasthealing 3 for the duration of that rage.
You gain one extra use of your rage ability per day and all your rages last for one round longer.
Fury of the Lion
Prerequisites: Anger of the Wolf, str 15, bab 5
Benefit: Everytime you enter rage, you gain the use of the cleave feat (even if you normally don't qualify for this feat) and the pounce ability for the duration of that rage.
If you already have the cleave feat, you gain use of the great cleave feat instead(even if you normally don't qualify for this feat) for the duration of that rage.
You gain one extra use of your rage ability per day and all your rages last for one round longer.