It's alright, i found a nice lifter ( Thousand ton Lifter) that worked great, but the lights are nor the problem, there's just too much parts, but when the lifter is gone, FPS are much more managable (30-40).
After some cargo missions to bring crew, escape modules, monopropellent extensions, etc... it's now around gilly and it works great, with it's 9000 delta V, it can go anywhere now !
Thank for your reply