You might almost be better off leveling up mining instead for the stamina bonus - the extra health throughout will give a better stamina cushion than a 2 minute heal. Or heck, do both mining and herbalism to get more health and more heals. Or roll 5x Draeni, make them all miners and herbalists, and then you get 2 heals + more stamina.

TBH, it's probably easier to just add a healer but that's a clever way to make non-healing groups work, cool idea!