I think that we may be able to deal with that by restricting ourselves to a single operation, closing the void portal after we know someone's recognized it but before the Inspired have time to inspect it carefully.
So, the plan is to make a noisy portal within sight of them. They should recognise the work of the Lady of Blasphemy. At this point, they can react three ways.
1) Pursue. Send out soldiers to find us, or maybe the two Inspired collaborate to create a tracker/sniffer/whatever Inspired thing to hunt us down.
2) Neutral. Hunker down, prepare for battle, have a sleepless night, maybe the Inspired work feverishly through the night to make anti Lady of Blasphemy weaponry
3) Flee. Forced march, double-time to get to safety.
Given that we're dealing with prideful Inspired, my bet is they'll go for 1 or 2. 2 is ideal of course, or attempting 1 and failing, but I'm concerned if they
don't fail when attempting 1. One of the Inspired has been in a wagon tinkering away for some time while the other rode up and down. Maybe he's working on an invention capable of harming/stopping us? They already positioned themselves in this way because they're worried about being ganked by us. It makes sense they'd be trying to work on countermeasures against us too, right?
If we give them warning, let them know the Lady of Blasphemy is nearby, and indeed coming after them, I'm worried that it'll be enough for their Inspirations to complete some project meant to harm us. That's why I wanted to set fire to their supplies rather than making it obvious that it was the Lady of Blasphemy coming after them. A couple of quiet portals and dropped torches, and no one will know for sure exactly how those tents got on fire. It's not like they'll starve or anything given how near to civilisation they are.