Hibiscus spiced rum?

[Bristolian]

My son has Caribbean heritage and loves travelling around there whenever he can. He's in his 30's and that generation seems to be stuck on cocktails.

He recently spent a fortnight in Tobago, and was recommended a local mix of spiced rum with 'sorrel shandy'. It was so good, he now can't get enough of it.

Turns out 'red sorrel' is Hibiscus petals.

I've searched the recipes here and so far I've only seen hibiscus in gin recipes - has anyone used it directly in a spiced rum, or should I just brew a separate hibiscus shandy?

From what I've read, it's a great flavour but needs quite a bit of sweetener (the petals are sold for herbal tea in the UK)