I got a few problems. For 1,2,3 enemy can get in with 1 bomb. also can be easly bomb jumped on top of then climbed. 4rd is the best I think.
Your goal when creating the way out the tower is simple, you want to force a knight that possibly gets in to have to use a bomb to get out, at the very least. The easiest way to do this is with a stone on the ground, a bridge above it, forcing it to be broken to rise, perhaps doors a bit above that and a notch if nothing, so that he has no way out without breaking it. The point is, the door, you might make it in time, but he also might get out in that time, if he does, he can win or come close, that's a problem, that's a weakness. Of all 4 of your variations you never have to break more than 2 door tiles to get out, in some of them with a good slashjump probably just 1, I haven't played enough to visualize the slash jumping off of ladders easily, sorry. It might not seem like a large weakness, but it really is when you face someone that can bombjump over and knows how to get out. Every single tower has a front ledge that I'd bomb jump up to and break the door on the way in or could easily jump over to get out as well, if you break the door it makes life easier, especially to access possible shops, if you jump over you could probably toss the flag back over if you have a friend waiting and you're good enough at it.
I think the goal is to delay them from getting past with the least amount of resources and time. All can be done with 1 bomb. Bombs are instant, so you can't repair it. Bomb jumping is also a problem because you put a staircase on top of it to let enemy walk over :D good job! If I see this in competitive matches, it will be a shame.
The reason it is here is cause mazey used this in a gather match and it worked. Because the other team was too busy laughing at it to figure out how to get past.