PS0 will NOT work on R4Ultra/R4SDHC. They are clone cards and use a custom firmware. You should know this by now if you have one.
PS0 is only playable on true R4s by YSmenu as stated in the first post. YSmenu will not run on R4Ultra/R4SDHC.
Your only option is to wait until the R4Ultra...
The thing is that the IATA rules impose a pretty hard limit of 100Wh on battery sizes for lithium batteries - and it doesn't look like Li is going away soon