What about adding CD32 standard controller to Amiga version? You can use then all 4 (or even 7 if required) buttons to actions.
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Ok, I had no time before today to check it, but now I'm doing this.
CD32 joypad control is working, but... is possibility to save custom control settings? Because default one are not fitting well in my opinion. But after remapping and quit settings are not saved.
Maybe also modify Amiga version to 1-7 buttons and in game menu not [off] [2-btn] [4-btn] but [off] [2-btn] [3-btn] [CD32]?