To be an SOT you have to run a legitimate business, so you’ll have to start making, or buying then trying to sell those weapons and I think but am not sure if you consistently do no business it can be taken away from you. Although you might be able to become a “content creator” and just post pics on instagram or something and be like “This is my business I’m an influencer\content creation”.

I say hook it up to a turret remove trigger entirely, then using a bluetooth module connect a PS5 controller, the triggers on those can force your finger back and you’ve just converted that full auto to an FRT design. Since you buy the turret then the kit separately all you have to do is keep the firearm in a separation location so the ATF can’t claim constructive intent. Then modify the drill mod\full auto upgrade so it has no trigger, uses the bluetooth controller, or you could modify the trigger to be instantaneous instead of an on\off, that’d turn it semi automatic. Then using a solenoid to push the trigger back forward you’ve got an electric FRT switch for it. Then assemble the entire thing as it’s not a machine gun. It’s worth noting I am not an attorney and I do not provide legal advise but I try to share what I think I know on that subject (CYA).

Use a solenoid valve that pushes the finger back forward after each shot. Simple since it’s already electronically fire control, then any micro controller would work. You might have to redesign the trigger group to accomplish that so it wouldn’t be a drop in but it’s probably easier then trying to use a purely mechanical solution.