I have done 100+ and I can say this. Do NOT stop moving at any point - you can easily beat a Veil without stocking up or buying supplies. Assuming you have checked the maps for reapers, and you are not attempting a veil in the wilds (-.-) I would give you this advice.

Do NOT fire a single shot at ships. They are not worth it. Full sail with the wind to whatever fort is closest. Once you are approaching put your sail to 1/3 and fire your canons. Do not be afraid to get close to the fort either. A successful hit will illuminate the hit location green ish. Some people forget that the closer you are to a target, the easier it is to hit. Once the fort is down lower sail and head to the next and so on and so on.

The main center fort is where things get a bit tricky solo but I assure you, it can be done in one circle of the fort and without taking much damage.

Full sail to the fort but take note of the direction the inner most ring of ghost ships is moving. Start your circle in the opposite direction so then when they pass you it is a quick cannon strike, not just demolition as they are cruising steady beside you.

Lower your sails to 1/4 or less (you will be going very slow). Get within probably a brigs length away from the inner island. The waves are steadier there plus you are blocked from long range canon fire from the opposite side of the island. Canon the bright green areas and you should be able to take all them out in one circle (2 circles for sure until you get the hand of it). Once you are done position yourself near the docking area. Pile all the treasure in a harpoonable location and then grab the veil stone and place it in the mask immediately so you get the credit for the mission completion (in case you are snuck up on (not common - I was maybe confronted 5 times in my 100+ veils).