I'm in the process of preparing the van for the old rustomeum treatment. I'm trying to remove as much as possible so I can remove any rust but the skirting on my van is proving a nightmare to remove.
I am trying to remove this section of skirting under the driver's door.

The screws that are holding it in place are completely rusted. I've tried the usual. Spaying with PlusGas, brushing off all the rust and crud and then taking an impact driver to it but they're just not budging. I wonder if there is a tip to these screws? They have some kind of clip which you can just see in the following pic.

I managed to get the ones holding the section at the front of the van moving but those ones just keep turning and not coming out.
Any advice welcome before I resort to the angle grinder. Not a lot of room under there so not keen on working with an angle grinder.
Thanks,
Tim.