Installing a sub panel
It's obvious you take your lighting seriously. You would be better off applying for and setting temporary power rather than trying to upgrade you existing service. It really doesn't matter how long you lighting stays on if it runs over two hours unless you are planning not to run anything else while the lights are on. Something like this could put a lot of strain on your service.

So what I would do is set a temporary service in an unobtrusive area and have the utility company activate it and deactivate it every year.

Good luck with your project and your neighbors complaints.