No need to combine them or lessen the task it takes to obtain that commendation.
Add new cosmetics at lower tiers, but don't take away the long distance ones.
You, personally, may not prefer it that way - but there are plenty of other cosmetics to be had. This game is about serving many, many different types of players with differing interests, motivations, and preferences. Some things that exist within this game will appeal to some players, and that will be at the expense of other players. And the reverse is true as well.
The developers have done a good job of keeping the balance more in favour of the quicker rewards, while having a few tasks/rewards that cater to the opposite side of the spectrum. And you're suggesting to change one of those few longterm rewards into a quicker reward.
Just as many of us have done, play the game and let those longterm achievements come as they may.
You're only focusing on one aspect - that YOU WANT those cannons. And you don't want it to take as much effort (and time) as it currently does.
And maybe the balance isn't right for YOU, but it IS right for some.
Some who want those cannons, as well, WILL enjoy taking that time and effort to obtain the rewards - and this will give them some focus, reason to keep playing, and continue their fun in the game.
The game isn't just made for me, you, or that guy sitting over there reading this right now. It's made for a whole crazy assortment of us. And not everything is about you or I.
Also, I'd hope there are new commendations specific to the Ghost Ships. And I'd love to see a longterm one for them. And maybe a commendation and reward for doing BOTH. That'd be cool, in my opinion.
Plus, I'd hope to see some easier rewards involved with them as well.
Cosmetics are the most desired rewards, and sometimes it is wise for the devs to use those to entice people to keep plugging away at some things.
It's also great to have rare cosmetics in the game that acknowledge the story behind that player having them. One look at certain ship cosmetics and I know that the player who equipped those things was on these seas during a particular event. Or I know they achieved a long-earned reward. This gives meaning and context to cosmetics that really makes this game feel like a living world.