You'll need to make a mod Even if its just ships.. there's no real way around it, more than one file needs to be altered and both client and server need be compatible.. A shipmod isn't hard, but you will have to learn what your doing with the .ini's
For instance.. If you took a ship & code from XLR (mymod) your game will crash untill you recode the shiparch data.. as i use things not native to Freelancer and have a ton of extra code in there.. that's just one mod.. others are even more reworked and have custom fuses, explosions.. all will crash if not properly cared for during transfer from one mod to another. FLMM won't fix any of that for you!!... you must do this by hand.
And of course.. if you should ever want to go pubic.. permissions and credits are also a bonus 8-)