No Simon, that's a bad Simon!

This is Simon (aka: Mr. Thumpy Clumperson) sulking after being repeatedly scolded for thumping every hour on the hour the night before.
Initially, I thought it was River making the noise because she's thumped before while having a nightmare and being deaf, didn't wake herself up.  To my sleep-deprived surprise, as soon as I checked River's cage, Simon decided to have an all-out conniption fit of loud thumping because I was ignoring him.  I rushed over to his cage to calm him down before he woke everyone within earshot.
I tried to scold him after realizing that he was doing this for attention by scooping up his front paws to ensure he was paying attention to me...he proceeded to happily lick my hand like an attention-starved puppy.
It was a long night because I had to stop him each time he started thumping by picking him up and saying, "NO thump, Simon."  Keep the command simple...bunnies seldom care about proper grammar (and at 4am, I didn't either).
Simon is lop flopping on my first attempt to sound proof his cage.  Turns out that it's pretty comfy.

Sadly, I think he took getting his own towel as encouragement.
Night 2 didn't play out much better.  More attention thumping (about 3 rounds worth of it).
I had decided to try a different tack--lay out the gray towel under his cage to help muffle the sound and not give him the attention he was seeking.  When he realized he wasn't being heard (we were ignoring him), he became louder.  Not cool.
I had to go out to stop him, but this time I got down on his level, blew a huff of air at his fur to get his attention (all the lights were off), then proceeded to turn my back on him and sit down for a count of 10, then walk away from him without acknowledging his presence.
Success!
This is bunny-speak for, "You really screwed up and I'm mad at you."  The fact that I didn't look at him afterwards told him he wasn't forgiven for his transgression.  At least the episodes of thumping were less than the night before.  Progress is good!

Day 3 I decided to get creative and if you look closely, you'll see that on top of the gray towel there is a slate colored pillow case just under the bottom of Simon's cage.  I decided to place about 12 layers of cut-up tee-shirts, sweatshirts, felt and that rubber cupboard liner stuff to damp the sound.
To hedge my bets after tapping the bottom of his cage and still noticing a good amount of sound, I placed shredded paper bedding under his hand towel to pad the bottom of his cage.
Poor River is confused why Simon is getting fussed over and wonders how come she can't have cool stuff in and under her cage too.  Short answer, she'd starve herself by hiding her food and never finding it again once it got mixed in with the bedding--she is quite the digger.

Night 3 I discovered that if you build a better bunny sound-proofing system, the bunny just cranks the volume up to 11.
Here is Simon at 2:53am having achieved his primary objective of waking the little human up.  It's like he's saying, "Oh, hi!  Well, since you're up, wanna play with some of my toys?  The cream cheese box is really fun to stick your head in and toss about--I even hang it off the side of my cage!"
I snapped the pic, then did the whole back-turn 'I'm ignoring you' thing.
Success!  That was the only time he thumped that night!
Hopefully this will be the last of it and I will have broken him of this bad habit.  Only time will tell.
UPDATE:  We think we figured out the problem--bunny separation anxiety.  Here's the link to my post http://bunnies-and-sunshine.blogspot.com/2013/07/who-knew-this-was-thing.html hope this helps!