Some people use one of the companions that they don't want in their party to learn crafting and blacksmithing. Each time you level you can ask a companion to leave and then recruit a companion left in the hall of heroes to level them (henchmen do not get a boost up to the player's experience when hired or re-hired, though).
It would be kind of a pain swapping equipment and materials back and forth, and heading to the homestead whenever you need to do any crafting or blacksmithing, but it would conserve ability points on your other characters.
