I've discovered what seems to be an alternative path to enabling exclusive mode. The windows 10 exclusive mode fix was not able to work on my machine for some reason, but this did. I found the configuration file for the generic HID game device at C:\Windows\INF\input.inf and temporarily added "AddReg = HKR,,Exclusive,0x10001,1" to the section [HID_Raw_Inst.NT], and then paired the ds4. This permanently enabled exclusive mode for at least that particular controller, although Input Mapper does not recognize it. Games that would not work with input mapper out of exclusive mode are now functioning properly again.
I'm unable to try the commonly troublesome games as my machine is fairly under-powered, but I have tried several games that were experiencing issues and they are now working properly. This trick is altering the way windows installs the default HID driver that provides access to the ds4, meaning that controllers installed with the alternate inf in place are permanently in exclusive mode, even without input mapper running, although I can't think of a situation in which this fact is relevant. With this change even the windows controller panel fails to register ds4 inputs while input mapper is running, which i believe it does not standardly do.
Exclusive mode with what though, exclusive mode describes the relationship between the hardware and the software that is accessing it, so for a controller to be permanently in exclusive mode that means its tied itself to something, I want to figure out more before I consider automating this as a fix built into the IM install process, people in this forum would never let me hear the last of it if I borked up some driver INF files lol.