Not sure if there is a Titleist employed rep in Hawaii, but if they need one...call me...

The Navy Base course outside of Honolulu and a muni in Hilo seem to be the best outdoor sites that do fittings. Both offer trial sets.

Would like to get clubs fitted from Titleist. When and where would be the next Titleist demo day? On Oahu?

This is a discussion forum for end users that use/support Titleist products. You likely won't get a direct answer.

However, if you go to the tab Clubs and click on fitting, you can find the 2 authorized dealers in/near Honolulu. You can call them to see what your options are. This is the link -
www.titleist.com/locator

My personal bias is to call the Navy-Marine golf course pro shop first. They do outside fittings and have trial sets. When they are listed, the pro shop should be open to the public even if the course is restricted by membership.