For what it's worth, I think far too much attention is given to opening theory in Diplomacy, and especially gunboat. Is the Lepanto effective? Yeah, sure. But not because it's some magical set of moves that nobody can deal with, but rather because of a fundamental truth in Diplomacy:
If I am attacked by my neighbors for an extended period of time in the early game and nobody puts pressure on those neighbors to stop, I will shrink and die.
There's no magic that fixes this situation -- it's simply a fact about the game. And, in gunboat, there's an additional advantage: an alliance in which each partner has an obvious responsibility for their own theatre minimizes miscommunication. For example, R/T cannot make progress against Serbia without both sets of orders meshing, which makes it hard in gunboat. However, a plan of Austria taking the land war and Italy taking the fleet war is much easier to understand, and an easy defensive line to hold. Attacking is harder, as coordination around Aegean is essential.
In a press game, it's sometimes possible to survive being jumped on by being clever, making threats about how your centers will be disposed of, yelling for help from neighbors of neighbors, etc. In gunboat, that's often not the case, and you simply have to accept that you will lose a minimum of 20-30% of your games in the early game without much recourse. A very poor player can make this higher through poor play, but my experience both on webDip and elsewhere is that this is pretty much a bare minimum -- sometimes you're Austria and everybody just wants a piece of the empire, or you're Russia and Germany decides to be unconventional and throw two armies at Warsaw in 1901 causing everybody else to jump in, etc.
Which brings me to the next point: what separates the strong players isn't their opening, but what happens next. In the late opening/midgame, it's the ability to read the board and see how things are progressing so that you are positioned correctly every time a power makes a new decision. Strong players might not have a much better 1901 or 1902 than weak players, but they have a much, much better 1905 in the games when they've survived to that point.
And, most importantly, the endgame. There's a saying in golf that you drive for show and putt for dough, and the same is very much true in Diplomacy. In this game, 5 players got a piece of a draw when the proper result probably should have been a French solo, and it was because of endgame tactics. For that matter, if France did not play accurately, it might well have been a 3-way or 4-way draw over the board. Think about that for a moment and ask where the points were really earned, using 35 pointts as a baseline number.
The "book" opening to this game, as clever as people might or might not have been, had a small effect on the final distribution of points -- it mainly served to harm Austria, who had no chance with three neighbors wanting a piece of him from the outset, and who even might have recovered later on if Italy had backed off more quickly. Everybody was still viable, even if some were a little bit ahead or behind (and that would go away anyway if players preferred for it to balance power rather than split it)
The early game, in which everybody responded to the situation on the board and eventually we figured out that it was England who would lose in the West and Austria in the East, earned 2 for each of the surviving players.
The midgame, in which we learned that Germany would be eliminated, while the endgame would look like France pressing for a win against R/T/I, would have earned another 2

for the remaining players. As it turned out, Germany got his piece of the draw, but presumably would not have if play continued until the outcome of the French solo push was determined one way or the other.
The endgame, on the other hand, was worth everything -- France would have earned 26 more points by taking his win, while the defenders would have saved those and kept their 9. For that matter, Russia might even have had solo chances if everything broke perfectly, right?
Given the above, where do you think you should be putting most of your effort as far as trying to improve? There's a reason that the pro golfers hit a lot more putts than drives in practice. I realize that the endgame is harder to practice simply because you have to get there first, whereas there's an early game every time you play. But I also strongly suspect that if we take a bunch of random gunboat games at the end of 1901, pause it, and let the weakest players draft which powers they want to take over, forcing the strongest ones to have the last pick, the strongest players will still come out ahead on average. I think it would be a good idea to think about having a SoW dedicated to positions that start in the midgame sometime for exactly this reason.