The problem with the KSG is that the inner caps on the ends of the magazine tubes are not easy to remove and that's the only way to get access to the magazines to clean or install magazine limiter plugs.
This is one weakness of the design.
The inner caps are secured with Loctite and removal usually requires mild heat and a special tool to unscrew the caps without damaging them or the threads in the magazine tubes.
There's a video on the Kel-Tec site showing the removal process, but I strongly recommend buying a better tool in order to prevent damage..........
I recommend NOT using the technique of a bolt and two nuts as a removal tool. That can do serious damage if there's a problem.
One way "might" be to use two thin wood dowels that will slip through the holes in the inner magazine caps into the magazine tubes.
That will depend on how big the holes in the magazine followers are. If the holes in the followers are too big, the dowel would slip through into the action.
With the gun assembled that might work, but it might also be a chore to get them back out.
The problem is as others have suggested is that you have to disassemble a lot of the gun to get to the tubes to put a dowel inside(not practical if you plan on using this for home defense). What I did was drill two holes in the tube caps and then threaded the holes so I could thread a long screw inside to “cap” the tubes to 1-3 rounds. Maybe one day I’ll do a post on this mod.