Silvers can be worth fishing for in a lot of the commercials as, in order to compete with carp they tend to feed shallow. It can sometimes be worth fishing on the deck for them but I prefer to fish shallow. Even when the lakes are frozen, roach, chub and skimmers still feed shallow. For this I think caster is the best bait but dont fish too short. There is no need to fish 5 metres as the fish are much bigger on shallow approaches so it pays to fish 12- 13 metres. Most rigs for this need to be sensible so either use dia .10mm or .12mm and size 18 hooks. Wide gape if possible due the odd carp that turn up. I tend to feed small amounts of caster very often and look to bring the fish up to 12-18 inches deep by regulating the feed. Try to avoid fishing on the drop as this will result in too many missed bites. Find a depth and stick to it. Bigger roach will hang themselves by doing this.
It is possible to catch very shallow as bigger roach feed very near to the surface. It might take them an hour or two before they get there though so its wrth lifting the rig out of the water and holding at a few inches deep to see if there are any signs.
Personally i dont break down to net roach as I find it easier to ship back to the pole tip and grab the elastic to lift the fish out. They tend to behave themselves better when you do this. Target weights will depend on the fisheries as some ohave more silvers than others but 30lb is achievable on many venues with 50-70lb possible on some. feeding is the key so you will need to keep it going in.