So I'm gonna go ahead and use this thread for what I figured out so far (as I'm also fairly new at the galleon).
1. The ship doesn't work when people don't listen.
2. When the ship is under fire, players tend to get overworked, as they get stuck repairing and repairing and repairing and so your ship dies a slow and painful death.
3. Aside from the light mount point on side and rear of the ship, the galleon doesn't have any armor removal tools.
So, as my understanding of this game gets slightly better every day I play, I tried solving this problem. So I started off with the chaingun on the left, combined with flak and lumber jack on left side and two carronades on right side. If this ship gets up close, it fights reasonably well and tends to get kills quite ok. Sadly, especially against opponents trying to force range (fieldguns, long range weapons, etc), you will be looking like an idiot trying to close the distance(which was pointed out by my teammates).
So I swapped out the lumberjack(which was not an explosive weapons and doesn't really hit all that well at long range) with a second flak and the chaingun with the fieldgun. This combo worked in 3v3, this was however with better players on my team piloting other ships, so I wasn't really decided on whether this loadout is good or not. Furthermore, this of course only works at long range maps, where your teammates can more easily scout for you and you're guaranteed to have a firing line if a square box shows up. Doing this, I can highly recommend circling counterclockwise as previously suggested. However, if the fight is on the edge of the map, you cannot circle around them because they will see you when you are hitting the edge of the map trying to pass them by. So when I get to the edge of the map, I reverse and circle clockwise with my left guns showing.
Now today, I tried playing this ship again, in 2v2. And quite sadly, I had little success with it. After yelling at my crew several times for not doing their job and them yelling back that they can't go any faster, I even found myself overworked to keep the ship alive. It has gotten so bad to the point that I considered running 3 engineers or maybe even 4 instead of just two. The added agony was worse of course when my teammates decided to just fly in, die to 2 very experienced captains and then decided to blame me for not flying in to help them.
So now, the ship's weaknesses, repairtime is horrible. It is so bad that a goldfish can permanently disable you and all you can do is beg your teammate to get him off of you. To deal with this myself, I tried tar. But it doesn't seem to do a whole lot when the ship is too close. At the same time, using a carronade at the rear CAN disable the ship, but often only after you've taken too much damage where you're unable to turn your strong weapons to them. As engineers seem slow to respond, turning with the phoenix claw seems to just make sure you lie dead in the air.
So this has been my dilemma so far. I did do some research afterwards trying to make sure one gunner can operate all 4 guns. He can, but he cannot use any special clips as the abandoned reload causes a clip reset. Maybe it is possible with the hwacha due to its very slow reload speed. If I find gunners willing to execute this and it being successful, I will let you know. I don't know what the burst damage loss is however and whether it will matter.
So if anyone has tips or recommendations other than to what I just found, I would appreciate it.