You can solve your lacking CON SKILL problem... By deleting CONSTITUTION.
1. Fold Con into Str.
2. Make a Constitution/Endurance skill under STR (atletics grapple endurance :here you go 3 str skills!)
3. Con saves are now Str saves. Making it a strong save.
4. Give players the full HD when leveling up. Boosts martials. Something they needed.
5. Players who wanted extra hp spend their ASI on Though Feat instead of Ability.
Thats all con does. Theres no actions in con. Its made important cause they wanted to keep it.