I carry a UV protectant umbrella. It really helps me keep cool and prevents sunburn, but I've also found that it's a great "weapon" against encroachers. If someone behind you is maskless or too close, you can angle the umbrella in a way that both discourages them from getting too close and (hopefully) protects you a little from any sneezes, etc., sort of like a face shield. You can angle that umbrella any way you need to, based on the location of the maskless person. If they're in front of you or beside you you can just turn your body to the side and hold the umbrella to the side that shields you from that person. Of course, there's not much you can do if you've got people from more than one side not wearing a mask or getting too close.
Most lines are roomy enough now that you can even do this in inside lines. I may get some funny looks, but no CM has told me to fold my umbrella. Maybe they think I really have extremely light-sensitive skin!