The space mission XP boost does not work. At least the last perk for an imperial char.
I bought the 1st 4 perks, did the mission (green), and it gave me 5830 xp at the end. Then I logged off.
The day after I bought the last perk and did the same mission (mugvaar ice field I think) and it gave me the exact same xp amount. I didn't level during that time and I stayed in my ship...