This seems like a great way to scout ahead. For instance, summon a rat, cast Beast Sense, and send it into the goblin's cave. The reason I ask is that a summoned creature is, in at least some ways, a spirit. Is it also enough of a beast for Beast Sense to work?

In related questions, while the caster can't see or hear, could they hold onto another character and follow them? Probably this would seriously mess up stealth. If they tripped, would it break their concentration?