You can mix esters just fine. If I was you I would go with the prop because it has a short half life and you only have 9 weeks between tests. You could run the prop for 6 or 7 weeks and then let it clear out for your test. Enanthate has too long of a half life for what you want. It needs to be ran for like 10 weeks or longer and it takes way longer to clear.
With prop you'll want to pin every other day.