Heh thanks. I will probabaly be back to converting engine to doubles, but this time with more conservative approach. Instead of trying to straight up convert everything to doubles I try to focus only on single part (Vectors), and make them compatibile with floats inside rest of engine.
As for collision I early figured out that PhysX is not up to task for solar system scale collision and ther would be needed custom physisc engine for collisions (tracing etc), and PhysX could be used only for local simulation of non critical parts of game (means, only visual parts).