Focus on multiple jobs possible with dedicated time slots
I learnt and I am still learning that we can focus on two jobs and still do really good at both jobs if we allocate time slots and stick to it, basically to have dedicated time slots. That's how I managed to work on the BI solution for EU Public procurement project (won 2nd prize at EU Datathon) without negative impact in my full time job, in fact I not only accomplished expected tasks but also came up with initiatives at my full time job.
So if you decide that night 10 to 12 is for a particular task. Then by sticking to it you will notice that the moment it is 10 your mind switches to it automatically and forgets the other one completely. Same way because you fix that the day time is for the full time job then there is no distraction from the other project.
So if you want to try something apart from your full time job then set a dedicated time slot for it and stick to it.