Ship size, what is reasonable?

As the game is continuously being updated, I've decided to focus on building a fleet of empty ships with plans to build out the interiors later. Continuing with this line of thinking, while I'm currently just building locally, I'm also only interested in building things that can be expected to run reasonably well on a server.

I understand this is difficult to estimate due to future updates that could improve overall performance, individual server power, etc, but, if you were to build a fleet intended for multiplayer, what would be the biggest entity you would make? Any other factors to consider that are worth mentioning?

I just don't want to build a monster that will never really see play hehe