I actually really like this idea, it's different from the usual stuff people want. It would be a very new system to TLOPO, seeing as we've never seen something like this before, so even if the developers took it upon themselves to work on this, it would be at least a year out.
They would also have to draft some restrictions and rules as regards the guildmasters choosing tattoos to be added for their guild, as that could probably be abused with racist imagery etc. (wouldn't put it past some of people in this game) and the same would apply to the custom sails, clothing, ships and whatnot. I'd like to see this in the game because as I mentioned, it is so different, but would also require a hefty amount of work that I don't think the team really has the resources to expend on such an endeavour.
Perhaps in the future we'll see something like this.