The 32-man limit in each system until a new instance is spawned is the key, and Achilles' Heel.
How I'd gatecamp, blockade, or shut down most routes if I was a Goon:
1. Put 20-30 people in highly trafficked but lightly policed systems. That is less than 32 people (duh), so any individual or small group jumping into the system would be in the same instance as the Goons.
2. Interdict the victims, overwhelm them with your superior numbers, blow the poor *******s up, take their loot, post killmail on EDGoonsFTW.com, collect tears on forums.
3. Rinse, repeat.
Haven't played the game (in Standard Beta), so no idea if the above is a workable idea. And I have no idea how to prevent the above - even concerted player-run in-game efforts would be futile, as any player policing force would just spill over to a second instance of the system.
edit: hmm, you could get around that by sending more than 32 minus [# of Goon in system]. The spillover players would spawn in a second instance of the system, and be safe from Goons.
Then again, if I were Goons, I'd have a secondary group of 20-30 Goons in a nearby system, ready to take over the second instance. Anyone saying "that's ridiculous, no on would go through that trouble" has never played against Goons. end edit
As to your suggestions:
A) The hated transponder or non-identificating of player ships. B) Random hyperspace spots, there's no one 'entry point'. C) Not giving corporation mechanics ever. For ever really good reason (like the First Great Expedition) there is another that will abuse the mechanics.
Won't comment on IDENT since I don't really grok the concept, yet, although I know it in broad strokes.
B might work, but with up to 31 people in a system and if interdiction (jump or SC) is ever an option, might not be enough
C will not work, period. There is no need for in-game grouping or corp mechanics due to TS and off-game forums and communication.
Same with trying to limit group or corp sizes. Goons would just form smaller groups, and collect them into platoons and companies, using TS to coordinate.
(3) Assuming they manage to get, say, 20 people in the same system across a number of instances, you only need ONE of them to be on your block list and you won't be instanced with them - assuming that works as has been discussed in the DDF. So you don't need all x-thousand of them on your block list, a decent enough selection of them will do.
Easy work-around: don't group up, organize via TS.