I use 100 lb fluorocarbon for fishing for musky. It works, but usually have to tie a new leader after each musky caught. For the small pike and pickerel, I use 20 lb fluorocarbon leaders. 12" is usually more than enough and I have caught many chain pickerel up to 27" on 20 fluorocarbon without losing one yet to them cutting through it. However, just like with the 100 lb for musky, you typically have to retie the leader. I usually buy 25-50 yard spools of it. They will last you a long time and make many leaders. I typically pre tie 10 leaders so I can switch them out without much down time.
Yes, they do make huge roadrunners. I have seen them mostly used for striped bass fishing, but I suspect there is no reason you couldn't use them for pike. But at 20", I don't think you need to use huge tackle... I like to use the Johnson Silver Minnow spoon a lot for fishing weedy areas for pickerel and smaller pike. It is weedless and you can run it through the thick crap without it getting hung up. Another lure I like is the Mepp's Timberdoodle. It too is weedless and can go through nasty thick stuff without hanging up. I've also had a lot of luck use the Berkley Gulp! Alive Jerk Shad. Rig them with a wide gap worm hook in the 2/0 range. Use no weight or a insert weight, like the one made by Lunker City. Stick the weight near the fat rear part of the Jerk Shad. When rigged like this, the bait has a crazy action and again, it completely weedless. You can cut the insert weight smaller or larger depending on how fast of a sink rate you want for fishing deeper water areas.
Good luck...
