arete, you make it unnecessary complicated.
Ok, let's start again.
1. You
absolutely must have your saves under DISCWLD\SAVE\ folder.
2. So you have two solutions:
2.1. Install game under DISCWLD folder, make SAVE subfolder, and always mount directory above this DISCWLD. For example, if game is on real C:\GAMES\DISCWLD, you need to mount C:\GAMES in DOSBox for play.
2.2. Install game anywhere you want, and make DISCWLD\SAVE
inside this folder. I.e., make another DISCWLD folder inside first one, then directory SAVE inside it. Now you can simply pull DISC.BAT into DOSBox to play.