I'm running a rope through a grommet and would like stopper knots on both sides so that the rope is secure and not movable either way. I've done an overhand stopper knot on the entering side then passed the rope through the grommet. I can do a similar knot on the exiting side, but I'm having a hard time cinching that knot tightly up against the grommet (see image). Is there some sort of slip stopper knot or similar that would allow me to tighten it? Or another method to accomplish what I'm looking to do?
To clarify, I'm passing only one rope through the grommet, one way. Once the knots are set, I won't need to untie the rope. And if there's extra rope on the bottom side after cinching the lower knot up against the grommet, I can cut off the remaining slack. Also, I wish to use only the rope, no other tools (clamps, etc.).