its one of those trial and error situations as is nearly everything in carp fishing,sounds like youre on the right tracks but dont use to powerfull addatives and dont put a lot of bait in your swim. to be honest i havnt had a winter session this year but i have found over the winters that i have fished to keep a constant but small amount of bait going in, on the waters i fish, i normaly hair rig a 10mm halibut pellet and a peice of plastic corn (in case the pellet comes off) or a 16mm halibut boilie (going against the general rule of winter fishing) and i put a few 6mm halibut pellets in a PVA bag the size off a 50p whith every cast, use a small lead ,1.5oz-2.0oz, so you can re cast more offten than normal, say every hour and catapult the odd boily here and there over the course of your session say 3-4 boilys every 30 mins but no more as too many freebies can be worse than having no freebies at all. thats my tactics any way, different things work for different people on different waters. dont be to concerened about the efficiency and how fancy your rigs are ,just make sure you use a good, sharp, reliable hook like korda wide gapes or fox arma point ssbp, you want to use the smalest hook you can get away with so try size 10-12 to begin with. Thats my thoughts any way, im sure there are loads of more experienced anglers on here that you can get better info off