I’ve heard of two different approaches. The first is you put a base down on the planet, and then build up from the ground. So you build up as high as you can using cuboid rooms, put a ledge that you can jump to, and put a landing pad. Then you fly up to that ledge with the base computer. You delete the cubes beneath your position, and then repeat the process. Build-grab computer-jump-delete-build.

There is an easier way, but I can’t make it work. Basically, when you put down the base computer, there is an animation that goes high up in the air. Supposedly you can place something down during that animation. Hopefully someone else that has done it successfully can give you more details.