Go for an AUG or a P90 then. It's not the sound leaving the barrel that is hard to suppress, but the gearbox and motor. The 2 I mentioned have a lot of space around it, so you can pad it with foam, etc. An AUG with a huge ass suppressor looks cool I think, so you can have the appearance too.
Then it's not worth the trouble.
https://cop9gun.com/prshop/en/jinggong-spares/150-jinggong-g608-foldable-stock-only.html?search_query=g36+stock&results=5
I second that.
Heat up a nail or a piece of hard wire red hot, push it in the plastic deep. Do this at least in 2-3 places, then use a soldering iron to smooth out the plastic. Then sand it, paint it.
Nice, but. As mentioned before, the issue is to collect and maintain the data of the sites. Unless you have a way of updating all game events all the time.
Something like this
http://www.ebay.co.uk/itm/12V-5A-Adaptor-AC-Power-Balancer-Charger-MYSTEKY-iMAX-B6-B5-LCD-Monitors-FT-/221810878332?hash=item33a4f5677c:g:ddkAAOSwDNdVjT7X
But with power cable
What foldable stock you have on the mp5k? Because if it's the PDW then you can remove the stock from the endcap, move the sling loop to an other hole and you get that what's on your link.
This:
GFC is GunFire Custom, meaning it's kjw in your case but they tinker with it. They relube, probably reshim AEG gearboxes, maybe change the spring and test it. I don't know what they do with gas guns, probably just relubing, testing.