Security system recommendations for 2006 Sportster

I just finished building a 2006 HD Sportster and it looks too nice, so I would like to add a sounding alarm to deter people from shaking it, and obviously walking it away. I do have a Chipolo locator already.

I would not want to have a separate item to carry (like a brake lock alarm) because this bike doesn't have any storage.

I'm torn between paying for the official harley TSSM or finding an aftermarket one but I know nothing about these things. Any recommendations are greatly appreciated.