Regarding 86Box: get disk images from WinWorldPC, and use Linux-y mtools to fake floppies. E.g. "mformat -C -f 1440 -v MYFLOP -i myflop.img ::" to create a 1.44 MB file and "mcopy -i myflop.img program.exe ::" to put stuff on it. "::" acts as the fake drive letter. You will have to eject / re-mount in 86box if you update the file.
Full disclosure: my 30 KB-ish executable is not yet a proper COM file. Currently trying to exorcise some "segment relocation" nonsense.