Position and scaling in space

Hello everyone,

I have been working on a small space game simulation and I have my spaceship moving in a local area quite well. I now want to expand my solar system to include a planet. This raised some concerns with regards to scaling and positioning.

In terms of scaling my game will have spaceships ranging in length from 5 meters to 3 kilometers and from 4 metric tons to 8 000 000 metric tons in weight. I wish to propel these spaceships forward using AddForce and am slightly concerned with the amount of force required to move my largest spaceship forward. Would this still be in the range of figures that the physics engine can properly handle or would I need to resort to some kind of size and mass scaling? If so, what would be a sensible function for scaling? Would a log scale make sense for instance?

With regard to adding the planet, they are obviously much, much larger than the largest spaceship so I can imagine I am not going to get away with simply plugging in the actual physical sizes of the planet. What sort of approach would you recommend here for making it look right however? I have read that some people decouple the physical positioning from the rendering and actually move the planet towards the player and scale it down to keep it looking the same. Is this a feasible approach in Unreal as well? What would you recommend?

Many thanks for your insights!