On DriveThru, the
Ares Dragon is available as a PWYW item for MgT 1e. The ship is a TL12 800 dTon mercenary cruiser with a 20 dTon launch.
If you're willing to do conversions from GURPS,
101 Starships has far more than 101 starships, and the ones that are GTL9 would probably be the best for conversion, since they're roughly equivalent to TL 9 to 11 ships. GTL10 covers roughly TL 12 to 15, so the bottom end could align with what you're looking for, but it could take a lot of sifting through entries to find that bottom end. I'd start with the Rule of Man vessels in looking at GTL10 ships, since those would date back to the Second Imperium. One nice thing is that they do full breakdowns of the ship components at the back of the document, so even if you're not sure what the equivalent to a particular system would be, you can see how large it is in GT and find something similar in MgT.