> they are not very tolerant for side-projects.
So... they have control over your _personal_ life/time? And you agree with this? Hopefully they pay you a LOT of money...
If your project doesn't compete with E-corp in any way, probably is not even worth mentioning it?
I'd recommend listening to this podcast: http://www.kalzumeus.com/2016/06/03/kalzumeus-podcast-episod...
It's on negotiation in general, not just salary.