After messing around for a bit, I discovered that the Tunnelers' level apparently plays a role in their ability to detect the player. So I lowered their levels, and voila: they no longer automatically home in to your location from out of nowhere the moment you try to sneak within their rather unbelievable range.

Lowering the Tunnelers' levels does not have any impact on their health or attack damage, by the way. Their deadliness in a fight is unchanged, only now they don't sense you magically. Also, with the levels I have set, the experience points they yield when you kill them remain the same.

Anyway, this is just something I quickly threw together after a little experimentation, and I have not tested it very much. But it seems to work, so I thought I'd just upload it here anyway in case anyone else finds it helpful. To install, simply put the Tunnelers.esp after DustSurvivalSimulator.esp in your load order.