Have you tried a dos box from the privateer directory, also are the editors located in the game directory?
Also, I dont think the editor "preasy" will function with the CD version, since that editor is looking for the old floppy .tre file versions. And in the floppy version, there are more than one .tre file. In the CD version, the individual .tre files were all packed into a single .tre file "PRSO.TRE" for P1 and "RF.TRE" for Rightious Fire add on. The editor "preasy" is written to look for the individual .tre files from the floppy version.
The editor "predit", should work with the saved game files of either version. I have done this before by taking old saved games from the floppy version and edited them and then placed them into the saved game slots for the CD version. I was even able to give the Centurion level 7 engines with level 7 shields for the Rightious Fire add on. Its a little tricky to do it, but it works.
However all of this editing was performed in a full dos boot mode. But I dont see why "predit" wont work with the saved games in win95 with predit running in a dos box. Make sure the editor files are in the same folder/directory as the game is and open a dos box and change the directory to where the game is installed (usually c:\privater. At dos box prompt type without quotes "cd privater" and hit enter)
The editor "prship"...I have no clue, but that editor is more than likely written to only look for the old floppy version .tre files and not the CD version .tre files.