big load of crap. Even #1 is a load of crap all by itself. If you can't see something you can't do anything about it ever. If everyone had to be in open, then people could set up patrols and guard the system. Every time you jump into a system you end up at the nav point, you will constantly by interdicted, and killed more than once, which means you will lose ships and money and might give it up.
It might not stop it, but it would make it a helluva lot harder for you to masuerade unharmed free as you like, without repercussions.
At best that's a delaying action. You might slow down an attack on your bit of the BGS but it's impossible to actually WIN it without engaging in PvE yourself, because the BGS -is- PvE. As long as one side is doing PvE and the other isn't, any amount of PvP will only make it take longer for the PvE group to win, you CAN'T make them lose by only engaging in PvP.
[edit] I'll draw you an analogy. Caveat: like all analogies, this one's not perfect. Please take it only as the illustration it's intended as.
There's a game of poker (BGS) planned. It's planned to happen in a room that has an infinite number of doors (instances). There's a group of a finite size that likes to play poker (PvEers), they intend to go in through the doors and play it. Your group (PvPers, also of a similar and finite size) doesn't like to play poker, you like playing tag and you especially DON'T want the other group to win at their poker game. Your plan is to stand outside the doors and try to prevent the other group entering by forcing them to play tag outside. Your hope is that the other group will become discouraged and leave. Sure, some might... but some players will NEVER encounter your group because they came in through a door you weren't watching, or because they were good runners and got around you, or coz you had to sleep at some point. Whatever the reason, at SOME point there'll be enough people inside the room that there WILL be a game of poker, someone WILL win it, and it WON'T be you coz you refused to play. The ABSOLUTE BEST you can manage with this tactic is to make it take longer for the poker game to be won, and the ONLY certainty is that YOUR GROUP WON'T WIN THE POKER GAME UNLESS YOU PLAY POKER.