If you are legiting and only injecting when undetected getting a VAC ban is unlikely but is ultimately possible. For the most part you only have to worry about Overwatch bans. To avoid these, tweak your config until it is still advantageous but not obvious to someone who would watch your replay. If you have never done an overwatch case yourself, watch a video of someone doing one on YouTube to know what people see as suspicious/red flags.
You should never play on an account that you are not comfortable losing, shit happens sometimes. You can purchase prime accounts with decent trust factor and playtime online.
Ultimately, the decision is up to you. Consider your risk level for your playstyle, what you have to lose, etc..
Good luck, have fun!
