After billions attempts I've finally managed to complete this level.
Spoiler ahead with a picture:
Spoiler
(https://i.imgur.com/9EmpKc7.jpg)
So this is how I did it:
The very beggining was to build a reactor on the middle white structure (just to the bottom right of the command node) since its ground lvl 10, it is safe for a long time.
Next I built 2 cannons, and move them to the place I noted on the image with the big arrow (please note that there are no canons on the image, because I took the picture after finishing the level and had already moved the canons).
Those 2 canons will hold the creep on that platform long enough for me to build a colector and a reactor to the white platform streatching to the left of the map.
After getting another reactor, I went with a 3rd cannon near the previous two, just to keep the creeper on hold. (I was constatly moving some of those canons, to "refuel" them, because units moving are not atacked by the "bugs")
After building some reactors on that left platform and having a decent flow of energy the level is really easy.
Hope this helps