I take it that your packet ship is the English version of that name, Packet as in a packet of mail?
On the west side of the Atlantic in the 1830's and 1840's a packet was the heavy carrier. They had their own hull form.
Three masts, minimal deadrise, a hard turn, and a slab side. Optimized for carrying capacity and efficiency. The point being that they probably used the lowest cost paint that could get the job done. Lamp black and white chalk may have been the low cost pigments. Maybe rust came in second.
If your packets were also a most with the least situation, I would guess that the paint choices would have been similar. If the routes were mostly cool or cold climates black would probably help with heat gain. If the routes were tropical, I wonder if white would help reduce the oven effect? I did a sail ferry at the North Carolina Outer Banks in August. I discovered one thing: there ain't no shade on a sail boat.
If you want your ship's captain/owner to have an imagination, you could experiment with a mixture of rust and black - a dark red.
Here is hoping that a bit of controversy gets you help from those with hard data. Otherwise, as long as you limit your choices to pigments that were available and in general use, whatever you chose would be as probable as can be expected.
