These days I just cheat and use *GURPS Spaceships*, which is mass-based
and has really clean scaling. If only it's combat rules didn't have
weirdnesses.
Honestly, GURPS Spaceships is really my favorite, especially with how well it scales. It’s even really simple to use.
But I like the gearhead aspect of Traveller ship building, so I’m trying to strike that comprise.