Yup, setpatch is needed to start AGA, but crossdos doesn't need AGA - it ran on 2.0 upwards (modern versio - there was a 1.3 version if I remember correctly)
Try doing the minimal startup mount env: envarc: loadwb,
go to storage/dosdrivers and run PC0 - it might run, though I can't test that.
The above startup is dangerous - any changes made to env variables will be permanent and it assumes everything is in the standard places (C S L LIBS etc)