I’ve been through the Panama Canal twice on my own boat, and I’ve sailed from Guam to Ireland, but not the other side of the world. I always carried guns and was just careful about reporting them...or not.
I did have to toss my guns overboard once. I planned to sail nonstop from San Diego to Panama, but ran into no wind for weeks on end and used much more diesel than I planned to keep moving. Rather than cross the Gulf of Tehuantepec with very little fuel left, we diverted into one of the last ports in southern Mexico. I deep sixed 3 firearms, none of them expensive.
But I’ve taken weapons into a score of countries, other than Mexico I had no hassle. I had no hassle in Mexico either, because I’d ditched the weapons. Sometimes I declare them, sometimes I don’t, depending on the country.
Flares as weapons are a joke. I’ve tested them against a jacket over a pumpkin at ten feet range. They bounce off leaving a scorch mark. They might, however, bounce off adn land somewhere and either start a fire or ruin a sail.
I would consider a 12guage steel converter sleeve that goes into a 25mm flare pistol. It turns the big pistol into a 12 guage firing real shot. Haven’t tried it but I like the concept, since the innocuous sleeve can be hidden easily, and so can some 12g shells.
Some of the flare pistols are fairly sturdy. You could likely sleeve it for a smaller caliber, such as a .410, much easier. Anyone with a lathe could make such a conversion. A .410 might be a little easier to shoot one handed, as well.
I think that I would like just about any modern scoped rifle for standoff range. Perhaps a .270 so it is not a “military” caliber. You can get a savage 110 brand new with scope for less than $600. If you shop a bit, you can likely pick up a used one for less than $400.
http://buy.auctionarms.com/10043723/savage-arms-corp-110-gxp3-270-win-with-accu-trigger