I'm thinking along the same lines as you mjp2, catch the first two sessions of the cricket, then head off at tea time in the cricket which will be 3:40, should be enough time to get to westpac and have a beverage or two on the way.
This.
Casuals will probably only choose one though.
As well as the Nix are playing right now, you would back the cricket.
Yep sadly you might be right. People won't pay for two lots of tickets. It's fairly ideal for nix season ticket holders, but most others will go to one or the other. Plus homegrown the day before doesn't help.
People can also go to the Phoenix on any one of 10-13 days a year. The black caps only play a test in wellington once a year. We only play India in nz every 4 years. We only beat them here...well...barely ever.