Another possible compromise: Mage 2E mentions that direct exposure to the Lie can sometimes cause an Awakening. Mage 2e also says that anything that can trigger Awakening could, instead, result in a Sleeper becoming a Sleepwalker. Put it all together and you get the idea that exposure to magic or the Abyss can (sometimes, unpredictably) turn Sleepers into Sleepwalkers.

So run your Sleeping hunters through a mindfuck scenario where they go up against a magical or Abyssal threat, to give them a taste of how terrifying Supernal magic can be. Then let them develop the Sleepwalker merit...