Simple Caster Limitation

[LordBlades]

clerics that mainly heal but carry some fun stuff to chuck around as well (after all if the cleric does the fighting, who does the in-combat healing?).

In combat healing is pretty terrible anyway, at least until you get Heal. From a mechanical standpoint it's much better to focus on killing the enemies ASAP and patch up afterward. Even if you do have a fighter, the cleric is much better off joining in on bashing skulls than hanging back and healing.

your method will make the fighter reach 11th level before the wizard and cleric reach 7th.

And it still won't help much, as a 7th level cleric, druid or wizard can do loads more than an 11th level fighter