Even in super large systems, some of my biggest planets weren't seen until within reasonable "rendering" distance.
On an educated guess, there are LOD settings for such objects. You just have to find the related files which are ini's I'm pretty certain. (that makes them editable with "notepad" .
One trick I remember seeing on new items was a simple LOD range setting of 0, 999999. But, I don't know how practical this is with items that have multiple LOD files. (such types increase level of detail as you get closer to them..you see this a lot in the standard game)
OP-R8R did an excellent job of this detail thing in the Sol System of the Crossfire mod. You can see trade lanes from a great distance. I could target them although I could not see them.

You can also try to increase draw limit, exe hack.
Look through "limit breaking 101" thread in editing tutorial forum, the post is sticky.
Hope this helps.

Got it, I've set all LODranges to 0,1000000000 in solararch.ini files and it dit it, all asteroids and bases are visible from far away like planets. I'm still working on base ships and tradelanes, the LODranges setting is working, but not enough...

Thanks for the tips everyone!