First, please think about where you post your threads. Second, as a coder, yes, this is somewhat possible, but at the same time, no. Just no. I'm saying no because of these reasons:

• As you said, major lag due to movement, glitches, redstone, etc.
• It will, in my opinion, be very hard to control the way I would plan to make it, so it wouldn't even be worth your time
• You shouldn't be able to drive it into enemy base, but if enemies claim it in wilderness, oh well, your ship is screwed up because you can't use your cannons or levers/buttons for redstone
• Ships crashing into each other or going onto land/island/structure will just break everything and was exactly the same reason why the original blimp idea was shot down
• People would find ways to exploit it, for example if the lowest level of water that ships could go in was y = 60, people would make their own oceans around their ports y = 80, thus having their ship underwater but not breaking the actual rule, and that would also look like grief
• Factions permissions would be bugged and Cayorion would have to fix that as well, which he nor anybody else wants to do
• Doesn't help RP that much if people build small rafts but shove in a horde of cannons connected to one lever which manually fires all of them at the same time. Ugly ships and grief would result