I've hired seniors - you'd be much better off replacing the 4+1 hour assignment with a 1 hour AMA or discussion about a project or ticket with the team they'd be working with and getting their feedback. Would they be able to work together?

Also, just post the salary!!! Seniors naturally will have made a wider range of life choices and will have a larger range of minimum salary they need to fund their lifestyle. Not posting it appears as if you're hiding something, which isn't a great starting point.