-The solution of "just hide indoors" is missing the point that looters have with the event in that they want to do what they enjoy, which is the PvE content of the game. Hiding indoors very clearly doesn't let you do that, unless you enjoy playing pretend with the npc in the tavern or store.
-The solution of "just go on quiet servers" is missing the point that looters have in that they want to mostly grind bosses, and to effectively do this, a group of people is preferable (but not required) and as stated earlier, when pvp players look for large congregations of people on their friends list, it doesn't matter if you are on Valor or Abassa, where there are players, that is a target. I understand telling them to go to gold room, but you can kill regular enemies as well as bosses almost all of the time based on the position of enemies in the game, so going to gold room is very often a less efficient way of looting, as well as if the looters are playing to actually get good weapons, then they all come from bosses, not gold room. I'd personally take Levi or Yore over the Emerald Curse.
-The solution of "just defend yourselves with the weapons you grinded for" is missing the point that some looters don't loot to use their weapons against players, they loot to use their weapons against other npc enemies in the game, and very often (as is such in my case) I loot for the collection, not to use them. My goal is to have a nice collection at the end of my time in this game that I can be proud of acquiring, not necessarily how many people I killed with it. This solution that is often spouted also doesn't take into account the complete imbalance of skill that is so blatantly present when you match up a normal looter vs a pvp player. Having good weapons doesn't mean anything when everyone on both sides just uses siege charge because yeeting it into a group of players means something is going to die, granted, this doesn't employ much skill on either side, but the players that got the drop on the looters have the advantage from the start.
-I do not think that most looters would mind actually playing a round of two of pvp during Muertos moon if you'd ask them, hell, I might even do it myself, but the issue is that (and there is literally videos of this) there are pvp players organizing ambush parties and then going in guns blazing, not even bothering to ask the looters to play a round or two of pvp, or to organize some looter vs pvp player event. This frankly makes it seem like the pvp players are simply doing this to disrupt the flow of gameplay for others, even if that is not their intention. The way in which they approach the event is basically pve, except in this case the e is the looters, as they do not expect to get ambushed and usually just stand still and take the death rather than react, because they know resistance is futile as they are at a disadvantage by all measures, and they might be tabbed out, afk etc. To flip their argument back on pvp players that is used on looters, "why do you kill other players if they don't realistically have a chance to react via ambushing them? at that point is it not just pve seeing as the looters take the loss right there and then?" is effectively akin to "why do you loot for these great weapons if you do not intend to use them in pvp?" Some looters do not find enjoyment in pvp, and I may be wrong in assuming the motives of the average pvp player, but I thought the fun in pvp was besting your enemy in a game of skill, not who throws the first siege charge or who kills the most unattentive looters. To me, it doesn't seem fun from either parties perspective and so one could be easily led to believe that pvp players ambush looters out of spite.
-If the solution you pose is to go sailing or stay inside, and you are targeting this at looters, than perhaps give the "looters" incentive to sail or stay inside, give them what you know they will want, add a new legendary weapon to be found at sea or something, people who tell looters to "just sail" or whatever, full well know they won't because there is no incentive to do so. If you tell looters to "stay inside" you full well know they won't as there is no incentive to do so, and so we just enter this same loop of ultimately players looting bosses, getting ambushed, dying, going to the forums to complain, pvp players responding with "lol" or "just go inside" and the cycle repeating.
With all of that being said, I don't think Muertos moon is a bad thing, and I don't think it has to be, but the complete lack of communication from the pvp players on this matter, in the form of asking looters to pvp, or organizing some event or at least SOMETHING is astonishing and defeats the purpose of the event, making it not "pvp" but "pve" as the looters don't care anymore from being ambushed and just stand still, die, and relocate. A lot of the solutions that have been mentioned are certainly viable, but at the heart of this issue is the community and how we behave towards this event and each other. We could certainly go with safe servers again, but with the diminishing population of the game. that would leave very little for people participating in Muertos to do.
TL;DR Neither side can win as looters won't put up a fight and will just stand still because they know trying to fight back is worthless, as they have been. and pvp players are effectively killing afk pirates / bots with no challenge, defeating the supposed purpose of pvp being the most skilled pirate winning, as they have been.