Your boilies sound too soft and inappropriate you need some specific hard hookbaits mate
Hookbaits are purpose designed, Sticky Baits ones are good and come in generous big pots they are useful if in any doubt
Coated braid will produce a thick knot but you can still use it
but you need a big hard hook bait, and drill the hook bait as well which helps stop baits fracturing, a small selection of drills are cheap, just get small name branded ones
rigging baits is faffy, takes time, you can experiment with different loop sizes use a ruler to measure out the loop and a gate latch needle to help tie them