One of my problems with large based ships, particularly the decimator and yv666 is that they look to flat on a single plane.

I would like to put them on a ball joint so if they bank or turn. I can tilt the model a bit so it looks more mobile. Any suggestions how to do this effectively

Games workshop used to have flight stands that ended in a ball along with a socket that attached to the model itself. Dunno if they're still available though.

This is also an option: https://community.fantasyflightgames.com/topic/131037-magnets-how-they-work-for-x-wing-miniatures/

Magnets!

Magnets!

This.

You might find NotBatman's thread helpful - available here: https://community.fantasyflightgames.com/topic/128587-magnets-how-they-work-for-x-wing-miniatures/?hl=magnets

Thanks for that, very useful post

You might try looking into rc aircraft parts. I'm fairly certain that some of the larger rc planes use ball joints for some control applications.