Use the old BOWEP verification movie* to set up the HDD, then run that HDD directly for playback.
70 FPS (DOSBox-x core default) for a game that actually internally runs at 20 FPS. Because of this, TASing is difficult, with inputs easily getting dropped, which is unusual for a game known for its forgiving input buffer. A multiple of 20, like 60 FPS, would be easier to TAS, better for accurate game logic, and turns out to be very similar real-time too.
* I prefer the newer verif file for its official SB16 MIDI instruments instead of FMSynth. Otherwise, the game is emulated fine in both.