Mo
This is a handy job, well done.
If you don't mind I'll be a little crictical
As hopefully you can see each plug has the inner core tube and the outer connector, I would suggest:-
You make sure that each outer is not touching an other outers- I looks as if one (at 11 o'clock) needs moving.
Put heathy amounts of solder on the outers, and your have no problem putting a tinned wire (wire that already has solder on it) on. On these to sleeving the wire isn't required.
The centres might not accept 79 strands of wire (check 1st), if they don't theb split the strands 50:50 and solder some in the centre core and some to the outer side of the centre core. With these wires, put some sleeving thats big enough to cover the post and soldered wires on before soldering.
You haven't mentioned the back box size, hopefully it's a nice deep one
.
You will need some slack on each cable to solder, the alternative might be to solder the plugs and then fit them to the faceplate- but each could be as difficult
If space is restricted behind the plate if the wires have a 'free and easy' movement beyond the back box, as you push the plate towards the wall, feed the cables back.
Alternatively try twisted the faceplate 180 or 360 degrees and you push it towards the wall, this will spiral the cables and may help in a tight spot.
What sort of camera have you got?